LETTERS ON TEEES. 



TREES AND THEIR NATURE ; 

OR, 

THE BUD AND ITS ATTRIBUTES : 



IN A SERIES OF 

LETTERS TO HIS SONS, 

BY 

ALEXANDER HARVEY, A.M. M.D. 

MEMBER OF THE MEDICAL SOCIETY OF SOUTHAMPTON ; LATE PHYSICIAN TO THE ABERDEEN ROYAL 
INFIRMARY ; AND FORMERLY LECTURER, SOMETIME ON THE INSTITUTES, 
AND AFTERWARDS ON THE PRACTICE OF MEDICINE, 
IN THE UNIVERSITY OF ABERDEEN. 



LONDON: 
JAMES NISBET AND CO. 21 BEKNERS STEEET. 

MDCCCLVI. 



EDINBURGH : 
PRINTED BY BALLANTYNE AND COMPANY, 
PAUL'S WORK. 




TO 



WILLIAM PULTENEY ALISON, 



M.D., EDIN. ; D.C.L., OXON. ; 
VICE-PRESIDENT OF THE ROYAL SOCIETY OF EDINBURGH; 
FIRST PHYSICIAN TO HER MAJESTY IN SCOTLAND ; 
EMERITUS PROFESSOR OF THE PRACTICE OF MEDICINE IN THE 
UNIVERSITY OF EDINBURGH; 
FELLOW AND LATE PRESIDENT OF 
THE ROYAL COLLEGE OF PHYSICIANS, EDINBURGH; 
ETC., ETC., ETC. 



TESTIMONY OF PROFOUND RESPECT FOR HIS PUBLIC AND 
PRIVATE WORTH, AND AS AN EXPRESSION 




IN 



OF PERSONAL REGARD, 



BY 



THE AUTHOR. 



PREFACE. 



The view given in tliese Letters of the nature of 
Trees^ although, in the main at least, the same as 
that first set forth by De la Hire, as long ago as 
1708, and subsequently held by Darwin, Mirbel, Du 
Petit-Thouars, Gaudichaud, and others, differs widely 
from that commonly received among us. It neither 
represents the popular belief, nor does it accord 
with the recognised doctrines of the schools. To the 
popular mind, indeed, it may be said to be nearly 
unknown, while heretofore it has failed to secure the 
sanction of the greater number of our scientific 
botanists. 



viii 



PREFACE. 



So little^ indeedj has the theory been countenanced 
by botanists, that, to take Professor Balfour's excellent 
Class-Booh of Botany (one of the fullest and most 
recent of our systematic treatises), as a fair exponent 
of the received doctrines in vegetable physiology, it 
may be questioned whether the notice there taken of 
the theory would lead any ordinary reader to do more 
than bestow upon it a passing regard, or would suggest 
to him the application here made of it (and obvious 
in itself) to two practical questions respecting trees — 
questions often put, and commonly felt to be ex- 
ceedingly perplexing, viz., To what age do they 
naturally live?" and, To what size do they natu- 
rally attain?" Certain it is, that in considering 
these questions. Professor Balfour himself makes no 
allusion to the theory, and seeks for a solution of 
them in a direction altogether different from that in 
which it points. 

It is precisely because our prevailing notions, both 
popular and scientific, differ so widely from what the 
author believes to be the truth on this subject, that 
he is induced to publish this volume. He is himself 



PREFACE. 



ix 



so convinced of the soundness of the theory which 
he advocates^ that he feels persuaded that all that is 
needed to secure for it a ready and general accept- 
ance, is to lay both the theory itself and the evidence 
in support of it^ fully and clearly before the mind. 
Thisj he ventures to submit^ has not yet been done ; 
and to this circumstance he would attribute the posi- 
tion which the theory at present holds. It appears to 
him^ thatj while^ on the one hand, some supporters of 
the theory have advanced arguments in its behalf 
which are really untenable, so, on the other hand, 
some of its opponents have erroneously imagined that 
they had disproved the theory when they had merely 
shewn the fallacy of those arguments. It appears to 
him, likewise, that in respect both of the arguments in 
support of it and of the arguments in opposition to it, 
too much has been made of considerations connected 
with the wood^ and too little of considerations con- 
nected with the hud. The former, indeed, seem to 
him extremely valuable, and he has taken full ad- 
vantage of them in his argument. Yet it is rather 
on the latter that he would rest the theory. The in- 



X 



PEEFACE. 



ferences to be drawn in support of it, from the nature 
and attributes of tbe bud^ seem to him so unassailable 
and so convincing^ that^ although he does not ima- 
gine thatj in the exposition here given of them, he 
shall succeed in carrying conviction to the mind of 
every one of his readers, he is not without a confident 
expectation, that among all classes of these, both the 
learned and the unlearned, the contents will greatly 
out-number the non-contents. 

Although continually spoken of in these Letters as 
his own theory, the author begs to disclaim all pre- 
tensions on the score of originality. He has advanced 
nothing that was not known or held before. The 
only merit he is disposed to claim in connexion with 
it is, that of having unfolded it more systematically, 
and in greater detail, than any of his predecessors. 
At the same time, he thinks it due to himself to state, 
that it was worked out by him, substantially as it 
now appears, without any assistance from others ; that 
it was embodied in the course of Lectures on Physio- 
logy, which he delivered in Marischal College during 
the winter session of 1844, without any recollection 



PREFACE. 



xi 



at the time of the views of M. Du Petit-Thouars ; and 
that it was subsequently more largely developed in a 
paper On the Nature^ Longevity ^ and Size of Trees^ 
which he published in the Edinburgh New Philoso- 
phical Journal" for January 1847, long before he 
had any knowledge of the writings of De la Hire, 
Darwin, Mirbel, or Gaudichaud. 

What led the author to direct his attention to this 
subject was, a difficulty he felt soon after he began 
his labours as a teacher of Physiology in 1840, in 
bringing trees within the pale of two laws universally 
regarded as applicable to all living beings — the law 
of a determinate duration of life, and the law of a 
determinate size of organism. His earlier inquiries 
disposed him to regard the difficulty as insuperable, 
and the laws as so far exceptional. After a time, 
however, two things drew him into the train of 
thought out of which the theory sprang. One was, 
reflection on the potato-plant as the produce of a 
stem furnished with hiids^ and capable of being re- 
produced from year to year indefinitely from buds 
alone, and the comparison of this with the results of 



PREFACE. 



slipping and grafting in tliose trees that admit of 
being propagated in that way. The other waSj re- 
flection on the entire absence in all vegetables of 
anything corresponding to the renewal of substaiice^ 
which is constantly going on in the living tissues of 
animals^ and by which alone their continued vitality 
is maintained. Once in possession of these two 
keys^ the whole theory^ as here unfolded^ gradnally, 
and without any sensible effort, took shape in his 
mind. The difficulty referred to vanished^ and the 
lawSj imagined to be exceptional, stood out in their 
character of universality. 

Trees being in themselves objects of universal 
interest — of interest even to the young, the author, 
while he has made it his first aim to treat his subject 
in a scientific spirit, has yet striven also to present it 
in a form, and in language adapted to the general and 
the juvenile reader. And, holding to the young per- 
sons to whom these Letters are more immediately 
addressed, the relation therein indicated, and writing 
under the promptings of that relation, he has not 
hesitated; as occasion offered, to introduce such ob- 



PREFACE. 



xiii 



servations as might lead them (and others of their 
tender years into whose hands this little book may- 
come) to associate Nature with God, and Natural 
Truth with Revealed; and^ in the words of the late 
venerable and revered author of the Essays on the 
Nature and Principles of Taste^ to look upon the 
universe which they inhabit, not as the abode only 
of human cares or human joys^ but as the temple of 
the Living God, in which praise is duC; and where 
service is to be performed." 

Southampton^ December 5, 1855. 



CONTENTS. 



PAGE 

LETTEE 1 1 

Introduction. Questions as to tlie natural longevity and size 
of trees. Footing on whicli these questions rest : twofold — 
Istf that every tree is an individual or single plant ; and, 
2ndly, that all living beings have a determinate duration 
of life, and a determinate size of organism. Grood grounds 
exist for believing that the latter assumption is well- 
founded. On the supposition that the former is also well- 
founded, nothing yet known as to the natural age or size of 
trees. Doubts as to the validity of the assumption. Ques- 
tion whether a tree is not in point of fact an aggregate of 
individuals — a body corporate, — consisting, at midsummer, 
of a collection of living yet perfectly distinct OMnual tree- 
plants, the produce of the year, and of the dead remains of 
a still larger number of individual plants of th e same species , 
the produce of preceding years ; the living plants evolved 
from huds and growing as parasites on the organic remains of 
the dead plants. If this be the real nature of trees, there 
will be no natural limit to their age or size. G-enealogical 
tree. 

LETTER II 11 

Inquiry as to the extent of our knowledge regarding the natural 
age and size of trees, on the assumption that every tree is 
an individual plant. The popular belief; vague. Infor- 
mation contained in systematic treatises on botany — by 
Professor Balfour, M. Richard, M. De Candolle : its un- 



xvi 



CONTENTS. 



PAGE 

satisfactory character. Information contained in books 
which treat expressly of trees, e.g., Griipin's Forest Scenery : 
equally unsatisfactory. Difficulties attaching to the in- 
quiry from the circumstance that we nowhere see trees 
presenting indications of natural old age, and that we see 
everywhere trees of great age — as old, in fact, and as 
large, as any of their kind have ever been known to reach — 
still growing as vigorously as in their earliest years. Re- 
markable statement in Isaiah Ixv. 22. 

LETTER III. 25 

Corporation-theory of trees resumed. Re-statement of this 
theory. The theory itself only a part of a more general 
theory in Vegetable Physiology. Statement of this general 
theory. All plants, even those called perennial, really 
annuals — some wholly disappearing by decomposition at the 
end of the year they are evolved, — portions of others re- 
maining for ulterior purposes in the vegetable economy of 
nature, but still remaining only as dead organic matter. 
AU plants evolved either from seeds or buds, or both. Buds 
equivalent to seeds, and merely fixed or adherent seeds. 
The produce of the buds of trees identical in character with 
seedling tree-plants ; and trees themselves merely the pro- 
duct of tree-plants issuing from buds and growing parasiti- 
cally on the persistant dead remains of the tree-plants of 
former years. Inferences : Is^, trees, as such, without 
natural limit to their age or size ; 2ndly, tree-plants, how- 
ever, live but one year, and attain to a comparatively small 
size. 

LETTER IV. ...... 30 

Subject continued. The persistent dead remains of the tree- 
plants of former years serve to the living and growing 
plants of the current year the purposes of a permanent 
mechanical support and of a temporary soil. Illustration 
of these statements as regards the two great divisions of the 
tree tribe. And, 1st, as regards the Exogen. Disposition 
of the plants as successively developed year by year in the 
vertical direction. Plan of fir tree. The bud at the sum- 
mit of the first year's plant sends upwards a new shoot and 



CONTENTS. 



XVll 



downwards new roots, these roots in their descent pass 
alongside the shoot and the roots of the plant of the pre- 
vious year, and thence extend a short way beyond into fresh 
soil. And so on. Disposition of the bark. The terminal 
bud and its relation to the pith contained in the medullary 
cavity. Qualification of the statement that the plants issu- 
ing from the buds actually send down roots. 

LETTER V. 89 

Examination of the parts composing the Exogen, as viewed 
horizontally or in the transverse direction. Cellular tissue. 
Relation of the woody tissue to the cellular. Medullary 
or pith cavity, medullary rays, medullary ring or cam- 
bium, and bundles of woody tissue. Disposition of the 
woody bundles often irregular — eccentric character thus 
given to the concentric woody rings. Gfrouping of the 
woody bundles into sets or parcels — columnar or buttressed 
character thus given to the trunk. Winding or erratic 
course of woody fibres or bundles. Identity of woody tissue 
above ground with that underground. Antagonism 
between the woody and the cellular tissue. Elm at North 
Stoneham, Hants, with roots filling up the decayed bole. 

LETTER VI. 49 

Examination of the parts composing the Endogen. The palm 
— disposition of its parts. Bud of palm — sends upwards 
leaves and fiowers, and downwards roots— these roots pass 
inside the remains of the palm-plants of former years. The 
palm-plant has no proper stem, and the palm-tree no pro- 
per trunk. Roots of the palm-tree fibrous like those of 
grasses, and derived from the palm -plants of the first few 
years. Aerial roots of certain palms, piercing through the 
trunk, passing down through the air into the soil, and form- 
ing props for the support of the palm-trunk. Slender hold 
which the palm-tree has of the ground. 

LETTER VII . 54 

Harmony of the Corporation-theory of trees with the known 
history of many trees still extant and remarkable for their 

h 



XVlll 



CONTENTS* 



PAGE 

age and size. References to very old and large 'trees — 
yewS;, courbarils, American cedar, boabab, gum-dragon 
tree, deciduous cypress, the banyan, enormous plank of 
timber, Wellingtonia gigantia. 

Question— "Why, if this theory be sound, very old and 
very large trees are not more numerous than they really 
are] Explanation— All trees subject to accidental" 
death from extraneous causes, and are sooner or later, and 
some kinds of trees more speedily than other kinds, thereby 
destroyed. Enumeration of these causes. 

LETTER VIII 68 

Evidence adduced in support of the theory. Two-fold — Is^, 
that the growths emanating from the buds constitute seve- 
rally perfect and independent plants, and that a succession 
of such plants may be kept up from year to year for ever 
from buds alone ; and, 2ndlyy that at the end of the year, 
the plants thus evolved (save the buds only) die and never 
live again. 

First branch of the evidence taken up and pursued. The 
produce of the buds includes all the parts entering into the 
constitution of the most perfect seedling plants, viz. : stems 
and roots, leaves, flowers, seeds and buds. The bud can 
evolve the seed. Illustrations furnished by the potato, 
the strawberry, and the processes of grafting, slipping, and 
layering. Mr Knight's view as to the dying out " of fruit- 
trees opposed to the theory : his view erroneous. 

LETTER IX 79 

Second branch of the evidence taken up- and pursued, viz. : 
that at the end of the year the plants emanating from the 
buds die. The only parts of the plants that then remain 
are the stems and roots, the other parts having dropped 
off. Proofs that these stems and roots die at the 
end of the year. Gfeneral considerations as to the very 
transient duration of vitality in all organised structures : 
the continued vitality of any structure only possible by a 
continual change of substance, called by physiologists in- 
terstitial or molecidar nutrition. This process obtains in 



CONTENTS. 



xix 



animals : does not obtain in any kind of vegetables. In- 
ferences. 

Additional considerations regarding the absence of this 
process of molecular nutrition in plants, intended to shew 
the identity between the perennial tree and the mere annual 
in respect of their vitality, and the difference between plants 
and animals. These considerations drawn from the different 
objects for which plants and animals respectively have been 
created. Obj ects of animal existence. Obj ects of vegetable 
existence — illustrations — corn-producing plants, timber- 
producing plants — the objects for which each of these exists 
accomplished year by year. Inferences as to the vitality 
of the persistent annual stems and roots of trees. More- 
over, after the year they are formed, these stems and roots 
undergo no change in the way of growth or extension. 

LETTER X. ...... 92 

The proofs hitherto adduced may be thought incomplete or 
insufficient. Although the stems and roots undergo no 
nutritive or other organic change after the year of their 
formation, the living sap moves or circulates through them. 
Hence a presumption that the parts in Question still con- 
tinue to be possessed of vitality. That presumption, 
however, erroneous. Why : the stems and roots of the 
previous year no otherwise concerned in the movement of 
the sap than passively and as mere channels of transmission. 
The circulation of the sap a vital process, and due to vital 
agency ; but this agency seated in the living and growing 
- parts — buds, leaves, ca^mbium, and spongioles of the roots, 
and the cause both of the ascending and the descending 
currents. No good grounds exist for ascribing vitality or 
vital agency to the old stems and roots. Further, in the 
course of time, these stems and roots undergo decomposition 
without this affecting the vitality of the growths siibse- 
quently evolved from the buds. 

LETTER XI 103 

Arguments in support of the Corporation-theory of trees, de- 
rived from the concurring and independent views of various 



XX 



CONTENTS. 



PAGE 

authors, e.g., M. Du Petit-Thouars, Mr Appleby, Dr Ware, 
M. Mirbel., M. Gaudichaud, Professor Owen. 

LETTER XII 122 

Objections to the theory considered. - Greneral nature and 
grounds of these. Nature of the woody layers annually 
formed in Exogens — these layers serve various purposes — 
still they are both virtually and actually roots. Mode in 
which they are evolved peculiar. Admission that they are • 
primarily formed in situ and from the cambium, as main- 
tained by Mirbel. Relation of the cambium to the bud — 
the cambium continuous with and an integral part of the bud 
— an extension of it in adaptation to the circumstances and 
objects of existence of exogenous tree-plants. Constitution 
and structure of the cambium — product of its development ; 
this not wholly evolved in situ— 2, certain portion growing 
and creeping downwards. This latter portion undeniably 
root and specially the rooi— the former, or that formed in • 
situ, a provision for bringing the root proper into relation 
with the shoot emanating from the bud. No natural or 
structural difference between the part above ground and 
the part under ground ; the tissue of the one continuous 
with the tissue of the other, and identical throughout with 
roots. Mode in which the cambium is developed into cel- 
lular and woody tissue. 

LETTER XIII 134 

Evidence in favour of the assumption that the woody layers in 
Exogens are of the nature of roots. Whenever circum- 
stances admit of it, the woody tissue of the trunk grows 
and comports itself as roots do ; processes of slipping and 
layering. North Stoneham elm, with roots filling up a 
chasm in the bole — other examples of this. Aspect of a 
piece of hardwood timber denuded of its bark. Relation 
of branches spreading southwards to roots spreading north- 
wards. Disposition of the woody fibres in the thorn, the 
poplar, the beech, and the yew. Spontaneous division of 
trunk of thorn into lesser stems. Fibres descending from 
a branch in Draccena and spreading over the trunk ; graft 



CONTENTS. 



xxi 



of Rohinia hispida sending down roots on dead stem of 
Robinia pseudo-acacia. Actual descent of woody fibres in 
the palm — virtual descent of these fibres in the trunk even 
of Exogens ; Dr Lindley's opinion as to this point. 

LETTER XIV 145 

Evidence continued. Unequal growth of the woody layers in 
the same tree in different years and on different sides of the 
trunk — these differences directly related to differences in 
the number of the plants emanating from the buds, to the 
vigour of the plants, and their position on the tree. The 
development of the cambium into wood dependent on the 
buds and their produce, i.e., on the leaves, and that in a 
way not referable merely to supplies of elaborated sap fur- 
nished by the leaves. The wood not wholly developed in 
situ. An actual as well as a virtual descent, in some way, 
of woody tissue from the leaves. Holly-and-chain piece. 

LETTER XV 155 

Dr Carpenter's objections to the theory. Partly general, partly 
special. In as far as general, various — these considered. 
Argument founded on an elm, referred to by him, con- 
sidered. Argument founded on the structure and consti- 
tution of the cactus considered. 

LETTER XVI 167 

Dr Carpenter's special objections to the theory considered. 
These twofold — 1st, that the buds and cambium -layer, 
and their respective produce, are merely continuous pro- 
ducts, and an extension of the existing tree. 2ndly, that 
the buds of trees are not co-ordinate with the seeds, and 
that only the produce of a seed can be regarded as an indi- 
vidual being. The former objection taken up and discussed. 

LETTER XVII 177 

Dr Carpenter's second special objection taken up and considered. 
The seed itself, in a like sense as the bud, merely an ex- 
tension or a continuous product of the parent plant. The 
bud can evolve all that the seed can. No real difference 
between two trees, e.g., two willow trees, raised, the one 
from a seed, the other from a bud. Exceptions taken to 



XXll CONTENTS. 

I 

this assumption, and allegation made that the bud repro- 
duces only its own variety of the species, while the seed 
reproduces the species itself. Alleged dying -out of the pro- 
duce of grafts. Other exceptions taken. Difficulties 
attaching to Dr Carpenter's view. Gremmiparous and ovi- 
parous reproduction identical in nature. A single cell the 
primary element in the reproductive process, and the bud 
the primary seat of this cell. 

LETTEE XVIII : 

Mutual relations of the bud and the seed. The two identical 
in their nature ; but the bud the primary mode of the re- 
productive process, and the seed a modification of the bud 
in adaptation to special ends : these ends, though they have 
a place in vegetables and animals generally, point to man 
and to man's moral and social nature and the institution of 
marriage as their primary source and origin. This view 
pursued at some length. Man's twofold nature and re- 
lations : an organised being and as such allied to plants 
and the lower animals and to the inorganic world ; a spirit- 
ual being, and as such allied to Gfod and the world that is 
to come. Uniformity or unity of plan observed throughout 
the whole of nature. Quotation from Professor Powell 
as to this. Application of the views advanced to the hypo- 
thesis suggested. The bud might alone have sufficed for 
reproduction, both in vegetables and animals, and even in 
Man. Adam, formed first : Eve afterwards ; Eve the off- 
. spring of Adam and evolved from a rib as from a bud. 
Reasons given in Scripture for Eve^s creation. Woman's 
mission. Inference. 

The bud at least co-ordinate with the seed : both answer 
the same end, but each in a way that the other cannot. 
How sometimes the one, sometimes the other, and some- 
times both together, are made use of by Nature. Import- 
ance of the bud in the economy of Nature — seen in timber 
and coal. 



LETTER XIX 

Practical applications of the Theory. Its uses in the ex- 



CONTENTS. 



xxiii 



planation of phenomena and in the solution of questions 
connected with trees — its uses to the gardener and the 
forester. Apology and protest. Suggestions. — I. Cautions 
as to pruning and precautions as to planting and thinning. 
II. The fact of the tree-plants of each year being essentially 
independent of those of past and subsequent years, aground 
of hope to the landowner that a disease affecting his plan- 
tations for one or even for a series of years,, may be but 
temporary and not permanently injurious. Disease in its 
own nature essentially temporary. Eecovery of diseased 
larch plantations. Probable final recovery of the potato, 
the h.op, the vine, and other plants from their " disease." 
Possibly some qualification of this expectation requisite in 
the case of trees — the timber produced by diseased plants 
perhaps unsound, and may affect the adjacent sound timber. 
'^Dry rot " in timber. 

LETTER XX 213 

Application of the theory to questions in natural theology. 
Laws of Nature : what they are ; various definitions given 
of them — Dr Alison's, Dr Thomas Reid's, Plato's, (Ersted's. 
' Illustrations. What the law written upon trees ; what 
the language which they speak. Conclusion. 

POSTSCRIPT 223 

Annual and prospective money-value of larch and Scotch fir 
plantations. 



APPENDIX 229 



LETTERS ON TREES. 



LETTER 1. 

As the days of a Tree, are tlie days of my People," 
Les Jours de mon Peuple egaleront les Jours des Arbres/' 

Isaiah Ixt. 22. 

March 10, 1854. 

My Dear Sons, 

1. The Winter is gone, and Spring is come again. 
The Sun, ''hke a giant refreshed with sleep," is again 
putting forth his strength ; and under his influence, as 
the instrument of Him who made and still upholdeth 
all things, " the earth is again rising as from her 
grave into life and beauty." What season more fit- 
ting to take up our favourite subject — the Trees, and 
to pursue those speculations regarding their natural 
longevity and size, and likewise regarding their real 
nature, which have so often, in the fields and by the 
fireside, formed the subject of our casual conversation. 
The buds on manj^ sorts of trees are already swelling, 
and the sap in the immediate vicinitj^ of the buds is 

A 



2 



LETTERS ON TREES, 



already in motion, — to be followed, ere long and in 
quick succession, by the evolution of leaf, and flower, 
and fruit, and wood, and root, and by a perfect circa- 
lation of nutrient fluid in all the living and grow'ng 
parts; and all this to be succeeded before the Tear 
has run its course, by the faUing of the leaf, the c^rop- 
ping of the fruit, and the cessation of all vital action 
in what remains. 

2. Taking up the subject now, ere yet the annual 
process of vegetation is well begun, and following this 
process through its several stages, we may have it in 
our power in the course of the season to make for our- 
selves observations enough, and experiments enough, 

, to satisfy us whether our speculations be true to 
nature and to fact. 

3. Of Trees in general, then, as of particular kinds 
of trees — for example, the Oak, the Elm, the Beech, 
the Fir, &c. — it may be asked, and often is asked, 
" How long do they naturally live ? " And, To 
what size do they naturally grow ? " 

4. Before proceeding to consider the answers to be 
given to these two questions, let us clearly understand 
on what footing the questions rest. To most, if not 
to all who entertain them, the questions proceed on 
the assumption that a tree is a single object, in a sense 
precisely analogous to that in which an ox or a horse 
is so regarded; they imply that every tree is as truly 
an individual being, corporeally regarded, as each of 



LETTER I. 



3 



us is ; and has as real a personality as belongs to our 
mare Fanny or our dog Ccesar. 

5. Nor is this all. They proceed also on the prin- 
ciple, that however the appointed term of life and size 
of organism may vary in the different sorts and species, 
all living beings without exception are subject to the 
law both of a determinate duration of life, and of a 
determinate size of organism. 

6. And this principle is unquestionably a sound one. 
No law of nature is more absolute or universal than 
the law of mortaUty. Everything that hves, be it 
plant or animal, lives only for a given time, on the 
expiry of which it passes into the state or condition of 
death. Nor is this left to be brought about by acci- 
dental causes. To these, indeed, it is often owing, 
the greater number — probably of all sorts — of living 
beings thus prematurely perishing. But independently 
of such causes, the loss of its vital properties, and the 
cessation of its vital actions, is a fundamental law of 
the constitution of every living being. The conditions 
of its existence include within themselves provisions 
for its dissolution. The arrangements to which it 
owed its origin, and by which its vital actions have 
been since performed, are such as unfailingly ensure 
after a time the extinction of its vital powers, — 

" Naseentes morimur, finisque ab origine pendet."^ 

Such changes are gradually wrought in it by the 



4 



LETTERS ON TREES. 



agency of its own vitality, as are ultimately incom- 
patible with the longer continuance of life. Death 
then follows as a matter of course. And those changes 
are attended by a gradually increasing languor or 
sluggishness in the vital processes, and by a corres- 
ponding hardening and rigidity of the textures com- 
posing the organism, — changes that constitute and 
betoken the state to which the name of old age is 
given ; a state which obtains uniformly when life is not 
prematurely cut short, and is indicative of the approach 
of death. 

7. Again, all organised bodies have an appointed 
size or bulk of organism. Of lifeless inorganic bodies, 
it cannot be affirmed that they possess any such pro- 
perty, being larger or smaller, to any conceivable 
extent, according as circumstances may determine. 
It is otherwise, however, with animal and vegetable 
organisms. These have naturally a fixed or standard 
size to which they grow, and from which they never 
greatly deviate. 

8. I have perhaps needlessly gone into these details 
respecting this principle. But I have purposely done 
so, and for this reason, that, while the principle is con- 
fessedly one of the grounds on which the questions 
before us proceed, and one which I hold to be unas- 
sailable, no answer that may be given to the questions, 
that is not in conformity with it, can be regarded as 
satisfactory. 



LETTER I. 



5 



9. If, then, every tree be a single or an individual 
object, it is plain that, by the laws of its being, it must 
have a determinate period of life, and a determinate 
size of organism ; and allowing that neither of these 
is absolutely fixed any more than in the case of the 
dog or the horse, but that each may vary within cer- 
tain limits, there must nevertheless be an average in 
respect of both for each kind or species of tree — it 
being of course understood, that all the conditions 
requisite for its natural life and growth, obtain. And 
accordingly, the questions before us thus qualified 
are — " How long does this or that kind of tree natu- 
rally hve V And, " What is the size to which it natu- 
rally attains ?" 

10. These questions, you may imagine, must admit 
of a ready and a satisfactory answer. True, you may 
feel yourselves unable to answer them, and yet reason- 
ably presume that our knowledge of all sorts of trees 
must be complete and accurate enough to make the 
answers easy to those possessed of that knowledge. 
They are not far to seek, speaking generally, as regards 
animals. Migratory as animals are, difficult of access 
or dangerous of approach as many of them are, these 
points in their history are accurately known, or may 
readily be ascertained in regard to a large proportion 
of them. How much more easily in regard to trees ! 
Fixed to the soil as trees are, remaining always on the 
same spot of ground in which they were first planted, 



6 



LETTERS ON TREES. 



or on which the seed dropt from which they sprang, 
continuing year after year, and from age to age, to be 
seen and read of all men living near them, — and many 
of them, in all parts of the world, allowed to live on 
and grow without let or hindrance, one would think 
that nothing were by this time better or more famili- 
arly known than the natural age and size of trees. 

11. It may very confidently be affirmed, however, 
that on the assumption stated as to the nature of trees, 
— to wit, that every individual tree is an individual 
plant, nothing definite or satisfactory has yet been 
ascertained respecting either the natural longevity or 
the natural size of any one species of tree — a circum- 
stance which contrasts remarkably with the precision 
of our knowledge, as far as it goes, as to these parti- 
culars in the case of animals, and all the more from 
the facihties which thus obviously obtain for making 
observations upon trees. Nay, more, there are many 
known facts in regard to trees which, on that assump- 
tion, it is difficult or impossible to reconcile with the 
principle of their subjection to the laws of a limited 
duration of life, and of a limited size of organism. 

12. But what if that assumption be a wrong one ? 
What if trees be not what they seem to be, and what 
most persons take them to be ? The common notion, 
as we have seen, is, that a tree is an individual in the 
same sense that a dog or a horse is, and it certainly 
appears to be such. It is assumed that the trunk, and 



LETTER I. 



7 



roots, and branches, the leaves, and flowers, and fruit, 
and buds, which form component parts of every tree, 
go to make up one and the self-same plant, in like 
manner as the bones and flesh, the nerves and blood- 
vessels, the heart and lungs, the head, and trunk, and 
limbs of a dog, do truly form the parts of one and the 
self same individual animal. Doubtless that is the 
common belief. A tree is regarded as having the same 
sort of individuality or personality that you or I 
have. 

13, My notion, however, of the nature or constitu- 
tion of a tree is widely different from this. In my 
view, it is not an individual in the proper or scientific 
sense of the term, but, on the contrary, a body corpo- 
rate ; and regarding it in this light, I hold that, but 
for purely accidental causes, any and every tree might 
live for ever, and go on growing and enlarging to any 
conceivable size. You have heard it said that the King 
of England never dies ; and you will readily under- 
stand that what is not true of individual men may yet 
be true of individual families, or of the race in general. 

H(EG NatuTCB lex, hoc consilium, iit singuli pereant 
homines, gens hiimana fioreat^'' — individuals die, but 
the race lives on and multiphes. The Corporation of 
London has lasted, one may say has lived, some hun- 
dreds of years ; and unless swept away by some such 
extraneous cause as an Act of the Legislature, may 
last till the end of time, although the individuals com- 



8 



LETTERS ON TREES. 



posing it may none of them pass the allotted three- 
score years and ten. 

14. Just so in respect of a tree. Take an Oak at 
mid-summer, in full leaf and in its full vigour. It is 
neither more nor less than a collection (an aggregate 
or corporation) of living and growing but separate and 
distinct oak plants, the production of the current year, 
and likewise of the dead remains of a still larger num- 
ber of individual plants of the same kind or species, the 
production of a series of bygone years. And of these 
oak plants, each and every one lives only one year, 
and attains its full growth within the year — making 
provision in the form of buds for the evolution of 
similar plants the following year. Further, the plants 
of each year, shooting up in spring from the buds 
formed by the plants of the previous year, grow para- 
sitically on the persistent dead remains of these. Ac- 
quiring their maturity in summer, and reaching to the 
height of a few inches only, they pass into the state of 
old age (the sere and yellow leaf) and eventually die 
in autumn, save only the buds they have formed, 
which survive the winter. And thus dying, the greater 
part of every one of them speedily undergoes decom- 
position, and disappears. The woody stems and roots 
alone remain. These, although dead, escape that pro- 
cess. Tipped with the living buds (as the ground may 
be said to be with the acorns that have dropped), 
they abide entire — as entire, yet as destitute of vitality 



LETTER I. 



9 



as the table I am writing at ; and tliey abide to serve 
to these buds and to the young oak plants that are to 
come of them next year (as the earth does to the 
acorns and their produce), the purposes both of a tern- 
porary soil and of a permanent mechanical support. 

15. Such is my apprehension of a tree, A tree is 
an aggregate of annual and comparatively small- sized 
and slender plants, the propagation of which from year 
to year is effectually provided for by buds ; and the 
accumulation of which en masse by the living growing 
as parasites on the dead, necessarily keeps pace with 
the annual succession of plants. And if what I have 
stated be a true account of its nature, and of the man- 
ner of its production, it will of course follow (as was 
before observed) that a tree is an individual in precisely 
the same sense as a body corporate ; and that, con- 
trary indeed to the common opinion, but in perfect 
consistency with the principle that all living beings 
are subject to the law of mortality, and have a definite 
size or bulk of organism, there will be no limit, except 
from extraneous causes, to the size it may attain, or 
the number of years it may live. 

16. What is called a Genealogical tree is constructed 
very exactly on the principle of this theory — or rather, 
as we must at present consider it, this hypothesis — 
and serves extremely well so far to make it intelligible. 
While the personality of each member of the tree is 
admitted, and his own individual temporary existence, 



10 



LETTERS ON TREES. 



he is yet regarded as forming a scion or branch of one 
common stock, which may have had its origin in a 
remote age. and may endure as long as the world 
itself. 

17. I dare say you have not been able fully to com- 
prehend or to take in, in all its parts, what I have now 
propounded to you. I shall be content, however, if 
you have acquired a general idea of it. In future 
letters I will go into it more in detail, and endeavour 
to make it good. — I am, &c. 



LETTER 11. 



Keculer pour mieux sauter." — Fkench Peoterb. 

March U.ISdL 

My Dear Sons, 

1. In propounding a new theory, it will often go a 
long way towards securing for it a more patient hear- 
ing, and for the proofs offered in support of it a more 
candid consideration, and in the end for the theory 
itself a more cordial reception, if, in the first instance, 
the theory to which it stands opposed be shewn to be 
unsatisfactory. This course I purpose taking with 
what may at present seem to you my strange theory 
of trees. Before going further into this theory, with- 
out at present even seeking more fully to unfold it, 
and still less to prove it, I shall assume that the notion 
commonly held as to the nature of trees is the right 
one, and, on this footing, proceed to inquire what is 
known in regard to the natural longevity and the 
natural size of this class of objects. The general 
result of this inquiry you may already anticipate. 
From the remarks just now made, as well as from 



12 



LETTERS ON TREES. 



what I stated in my former letter, you can scarcely 
fail to see what the general conclusion is to which I 
intend to lead you. Let us endeavour, however, to 
follow out this inquiry fairly and without prejudice, 
and (as I once did) without any such anticipation as to 
the issue. 

2. Viewing, then, every individual tree as an indi- 
vidual plant, let us inquire what is known or believed 
in regard to those particulars in the history of trees 
which have been already specified. How long does 
the Oak," for example, naturally live " To what 
size does it naturally grow ? " 

3. The popular notion seems to be nearly limited to 
this, that, as compared with any known animals, the 
greater number at least of trees are very long-lived, 
and capable of attaining to a very great size. It is 
believed, indeed, that, in common with all other living 
beings, they are subject to the law of mortality, and 
grow only to a certain size, and perhaps that the 
appointed term of life and measure of growth vary in 
each species of tree ; but beyond the general fact just 
stated little appears to be known ; nay, there seems to 
be a general persuasion that nothing definite has yet 
been ascertained on the subject. If you ask, as I have 
often asked, an intelligent old forester, who has passed 
all his days among trees, what he knows of the matter, 
he will probably tell you that he knows nothing. He 
may remark of the Larch, for instance, that, growing 



LETTER II. 



13 



along with other larches in a plantation, it reaches its 
maturity, or becomes ripe," in seventy or eighty 
years, and after that does no more good. But he will 
himself observe also, that the history of a larch so 
reared gives us no insight into its capacities for life 
and growth, and will point to numerous examples of 
larches growing singly and alone, which have already 
lived twice that period, are still growing, fresh and 
vigorous as ever, and are still enlarging in all direc- 
tions. 

4. Systematic treatises on Botany may reasonably 
be supposed to contain the wished-for information. It 
will be found, however, that but little information is to 
be had from them, and none that is satisfactory. For 
the most part, the subject is passed over in silence; 
or, if treated of, the observations made are of the most 
meagre description. One of the fullest, and best, and 
most recent — that by Professor Balfour of Edinburgh 
— makes no other than a cursory allusion to it, brought 
in, moreover, indirectly. There is still wanting defi- 
nite information as to the age which trees attain. The 
duration of their life has not been accurately deter- 
mined. It exceeds so much the limit of man's life that 
it is not easy to collect data on the subject. Some 
exogenous trees attain a very great age. Trees, 
which, in individual cases, attain great ages, belong to 
the most different natural families. Among them may 
be mentioned the Boabab, the Dragon-tree, species of 



14 



LETTERS ON TREES. 



Eucalyptus, Taxodium distichum, Pinus Lambertiana, 
Hymenaea Courbaril, species of Csesalpinia and Bom- 
bax, the Mahogany-tree, the Banyan, the Tuhp-tree, 
the Oriental Plane, Limes, Oaks, and Yews." * And 
again — The age which trees attain has not been fully 
determined : some live for many centuries." f 

5. As regards the size of trees, Professor Balfour 
observes — " Many coniferous trees, as the Larch, the 
Scotch Fir, the Norway Spruce, the Weymouth Pine, 
the Red Pine, Douglas' Pine, Lambert's Pine, the 
Norfolk Island Pine, and other Araucarias, have stems 
varying from 100 to 200 or more feet in height. Dico- 
tyledonous forest trees in Britain, such as the Oak, some- 
times attain the height of 120 feet. Forest trees, on 
the Continent and in America, are sometimes 150 feet 
high. Monocotyledonous stems, such as those of Palms, 
are usually unbranched, and their height is sometimes 
150 or even 180 feet. Acotyledonous stems, as those 
of species of Alsophila, Dicksonia, and other Tree- 
ferns, attain a height of fifty or sixty feet." % " Stems 
often attain a great thickness. The stem of the 
Drao'on-tree of Orotava is seventv feet in circum- 
ference ; that of the Boabab has a circumference of 
ninety feet. Some Cedars of Lebanon at the present 
day have a girth of forty feet. Chestnut-trees have 
occasionally a circumference of sixty feet, and trees of 

* Class-Book of Botany, p. 667. f Ibid, p. 669. 

X Ibid, pp. 436-438. 



LETTER II. 



15 



the South iVmerican forests are mentioned by Martius 
with a girth of eighty-four feet at the base of the 
trunk." * 

6. What do we learn from these statements ? The 
height and thickness which individual trees of dif- 
ferent sorts have been known to attain. But nothing 
approaching the expression of a law. And doubtless, 
of the trees specified, the measurements of many of 
them were taken at a time when they were still grow- 
ing in height, and still increasing in thickness ; or if 
dead, reduced to this condition by the axe of the 
forester, and felled while yet fresh and vigorous. 

7. M.Richard, in hhWoiiveaux EUmens de Botanique, 
goes more expressly into the subject than Dr Balfour. 
He has sections designated respectively " De la Duree 
des Arbres/' " De la Hauteur des Arbres" and De 
la Grosseur des ArbresJ'f Let us see whether now 
we shall get the information we are in quest of. In 
the first section, M. Richard merely tells us that trees 
growing in a suitable soil may live for ages — the Olive 
for about 300 years, the Oak for about 600, the 
Boabab, according to the reckoning of M. Adanson, 
for about 6000 years ; and further, that the Cedars of 
Lebanon appear to be in a manner indestructible. 
'^Les cedres du Liban paraissent en quelque sorte 
indestructibles." Mark this singular expression. In 

* Class-Book of Botany, p. 438. 
t 5ieme Edition, pp. 130, 131, 132. 



1(J 



LtTTEKS ON TREES. 



the second, he says, in general terms, that certain 
trees acquire, after many years, a considerable height 
and thickness, and m particular, that the greatest 
increase m height which the forest-trees of France 
arrive at is from 120 to 130 feet — those of America, 
however, often exceeding 150 feet. And in the third 
section, he observes that the trunks of individual 
Boababs have a girth of ninety feet ; the trunk of a 
Dragon-tree in the Canaries, a girth of forty -five feet ; 
that of a Sycamore in South Carolina, a circumference 
of sixty-two feet ; and lastly, that in France certain 
trees which he specifies have trunks with a girth of 
from twenty-five to thirty feet. 

.8. We are still, I fear, as far off as ever from the 
discovery of the laws which we are seeking to ascer- 
tain. Let us turn next to M. De Candole, and inquire 
of him what he knows on the subject. This eminent 
botanist has written largely and very expressly on 
the longevity of trees. All that I happen, however, 
to know of his researches, is what is to be met with in 
our Enghsh works on botany, and these merely give 
us the result of his examination of certain trees, toge- 
ther with details as to the method he followed in his 
estimate of their age, and the data he supplied for 
computing the rate of growth, and consequently the 
age, of trees generally. His way of getting at their 
age was to count the number of annual layers or rings 
of wood — reckoning, of course, at that part of the 



LETTER II. 



17 



trunk on a level with the ground ; or, having ascer- 
tained the average rate of growth, to deduce the age 
from the thickness of the trees. This method, it may 
be observed, is applicable only to exogenous trees, 
and even as regards these is beset with certain fal- 
lacies, although on the whole, and for general pur- 
poses, it is sufficiently accurate. Subjoined is a table, 
drawn up by himself and others, of the ages of cer- 
tain trees : — 



Elm, . 


355 years. 


Cypress, 


350 ... 


Cheirostemon, 


400 ... 


Ivy, . 


450 ... 


Larch, 


576 ... 


Chesnut, 


600 ... 


Orange, 


630 ... 


Olive, . 


700 ... 


Oriental Plane, 


720 ... 


Cedar, 


800 ... 


Lime, . 


1076, 1147 ... 


Oak, . 


. 810, 1080, 1500 ... 


Yew, . 


1214, 1458, 2588, 2880 ... 


Taxodium, 


3000 or 4000 ... 


Boabab, 


5000 or 6000 ... 


Dracaena, 


6000 ... 



9. Now, what is the real import of this table ? What 
the precise value, in relation to our present inquiry^ 
of the data suppHed by De Candole for estimating the 
age of trees ? What we want to know is, the natural 
longevity and the natural size of trees — their average 



18 



LETTERS ON TREES. 



natural term of life, their average natural height and 
girth. On these points, I apprehend, we are left by 
De Candole as much in the dark as before. His table 
is simply a list of certain trees which, at the time they 
were examined, had, or were supposed to have, at- 
tained the ages specified. Many of them, doubtless, 
were then alive, and not a few of them probably still 
growing, if not in height, at least in thickness. Per- 
adventure (the case is quite conceivable), according to 
the theory of trees at present assumed to be the right 
one, some of these trees had even exceeded the natural 
age and size of their kind — had as far surpassed it as 
Thomas Parr, who died at the age of 152, or Petratch 
Zortan, who lived to the age of 184, exceeded the 
natural age of the human species, — or as Charles 
O'Brien, who stood 8 feet 4 inches, and Daniel Lam- 
bert, of whose prodigious weight and bulk every one 
has heard, exceeded the natural weight and size and 
height of the race. In short, neither the table nor 
the data of De Candole take any account of, or have 
any bearing upon, the average natural duration or 
size of trees. 

10. One other source of informiation yet remains — 
the books which treat expressly of trees. Of such 
there is a considerable number. It may suffice to 
instance one of the best and most widely known — 
Gilpin's Forest Scenery^ and the late Sir Thomas Dick 
Lauder's edition of that work as being singularly 



LETTER II. 



19 



copious in supplementary details. In works of this 
kind especially, even more than in systematic treatises 
on Botany, one might expect to find the desired infor- 
mation. My o.wn examination of them, however, has 
been to no purpose. They enter largely into the 
history of all or most of our British trees, and into 
that of many foreign trees ; and they abound in details 
of exceedino* interest reo^ardino; those that are most 
remarkable for their age or size, their historical asso- 
ciations, their beautiful forms or fantastic shapes, their 
modes of growth, &c. But they are absolutely barren 
of information bearing on the questions before us. 
They give us no insight into the allotted duration and 
size of trees. They do not even acquaint us what the 
extreme limit is to which their lives may be protracted, 
or the extreme height and thickness to which they 
may attain. 

11. The fact indeed appears to be, and it is one 
which stands out in striking contrast with the particu- 
lars furnished by Balfour, Richard, De Candole, and 
others, as to the ao-e and size of trees, that in many 
different parts of the earth there are individual in- 
stances of almost all kinds of trees, which have not 
merely already stood as many years and grown to as 
great a size as any of their species have ever been 
known to do, but (which is peculiarly remarkable, and 
indeed singularly striking), are still vigorous and 
growing, and as yet exhibit no signs of what can pro- 



20 



LETTERS ON TREES. 



perly, that is, physiologically, be regarded as old age. 
Of many of these " oldest inhabitants of the park, or 
the church-yard, or the forest, much of the trunk may 
be hollowed out ; many of the larger branches may 
have been broken off or otherwise destroyed in the 
course of ages. The sundry and manifold changes 
of the world" may have shorn them of their glory and 
left little of them remaining. Still that little evinces 
as great activity in the vital processes as ever. That 
is to say, it is the seat of as vigorous a circulation of 
sap as in its earliest years ; it puts forth and matures 
leaves, and flowers, and fruit, which are as large and 
as perfect as in its best days ; it is still forming fresh 
wood, and having every year additional bulk given 
to it. 

12. Let one example suffice meanwhile. There is 
at Allonville, in France, an oak so decayed, that the 
only support it has is by the outer layers of wood and 
by the bark. It may be said to stand on stilts. Its 
trunk is a perfect hollow or cavern ; and some idea, 
both of the size and age of the tree, and of the extent 
of its decay, may be formed from the fact, that in the 
year 1696 its hollow stem was converted into a little 
chapel of six or seven feet in diameter, wainscotted 
and paved, and in which Divine service is said to be 
still occasionally performed. It is computed that this 
tree, which is upwards of thirty-five feet in girth, 
must have seen at least from 800 to 900 summers. 



LETTER II. 



21 



Yet it is still vigorous. Every year " it is adorned 
with abundance of leaves, and laden with acorns." 

13. The considerations now stated, and others to be 
adduced hereafter, when they will be better appre- 
ciated, can scarcely fail to suggest a doubt whether 
there may not be some peculiarity in trees as regards 
their longevity, beyond merely a very prolonged ex- 
istence ; nay, although according to the view com- 
monly taken of their nature, it were absurd seriously 
to entertain the idea, whether there may not be in 
their case a virtual, if not an actual, exemption from 
the law of mortality. Some such idea may not un- 
reasonably be supposed to have been present to the 
mind of M. Eichard, when he remarked of the Cedars 
of Lebanon, that they appear to be indestructible — 
an expression which, if it have any meaning, is equi- 
valent to saying that they appear to live for ever, and 
would imply that the law of mortality is not univer- 
sally operative. 

14. Such is the present unsatisfactory state of our 
knowledge respecting the natural longevity and the 
natural size of trees — regard being had to the popular 
belief as to their real nature. In the case of each 
species of animal, the natural term of life, and the 
appointed size of organism, are either known to us, or 
may, with comparative ease, be ascertained by us. 
But with respect to trees, these particulars in their 
history may fairly be said to be absolutely unknown 



22 



LETTERS ON TREES. 



to US, — and that, too, as I before observed, notwith- 
standing the facihties within our reach for making 
observations in regard to them. Each one of every 
species is looked upon as a single individual in the 
same sense that each one of every kind of animal is so 
regarded ; and while it is believed to be subject to the 
law of mortality and to the law of a determinate 
stature, it is believed to be also, as compared with any 
known animal, very long-Uved, and capable of attain- 
ing to a gigantic size. No more precise idea, however, 
as to either its longevity or its size is entertained or 
seems possible ; and even this conception of both is 
beset with considerations of perplexity. 

15. It is no doubt true, as Professor Balfour ob- 
serves, that the duration of the life of trees exceeds 
so much the limit of man's hfe, that it is not easy to 
collect data on the subject." It is true, also, that even 
were "tradition" more to be relied on than it is, 
most trees are already old before they come to be 
objects of historical interest. But their past history 
is not therefore buried in oblivion. And it is a suffi- 
cient answer to both the difficulties now started, to say, 
that every tree carries within itself the record of its 
birth and of its career through life. Each year that has 
passed over it has left its impress upon it. We have 
only to count the cylinders of wood it has gathered 
round it, to know how old it is — to examine the thick- 
ness of the several cylinders, to determine what the 



LETTER II. 



23 



character of the seasons, and the circumstances under 
which the tree has grown, have been. The real diffi- 
culty lies in this — that we nowhere see or can discover 
trees presenting indications of their having passed the 
limits of their natural growth, or lapsed into the state 
of natural old age. Examine the oldest known tree 
of any species : take, for example, the tree at Pear- 
tree Green, in this neighbourhood, the trunk of which 
is now reduced to a mere band or strip of wood and 
bark, and which can stand only (or rather, as it does 
in fact, rechne) by the help of a crutch. You will find 
that so much of it as yet remains is still extending its 
roots and lengthening its branches— is still forming 
new wood and bark ; while, further, the leaves which 
it sends forth year by year are as large, and the cir- 
culation of sap through it as vigorous, as in the days 
of its youth. 

16. But if my theory of trees shall prove a sound 
one, this and every other difficulty will be obviated. 
And it will then appear that a book which I have not 
yet named, the oldest known book extant — the Bible — 
gives a far more satisfactory answer to our questions 
than is to be met with in our scientific treatises. " As 
the days of a tree are the days of my people." * That is 
to say, the days of a tree are naturally indeterminate 
— without set limit — in the ordering of Nature ever- 
lasting. In this lay the significancy and the value 

^ Isaiah Ixv. 22, 



24 



LETTERS ON TREES. 



of the declaration. Possibly, however, it may have 
been of wider import, and have embraced a larger 
view of the nature of the tree. The tree, rather 
than the "everlasting hills," may have been made 
the basis of the declaration, as being possessed of 
only a contingent perpetuity, — in its own nature 
most truly perennial, yet subject to decay and ruin. 
And so the declaration may have carried with it an 
admonition and a warning, as well as a gracious assur- 
ance ; and have been so intended and understood. 
Looking at it, at least, from our present stand-point 
in time and in the light of history, it is scarcely pos- 
sible to read it otherwise. " The days of my people 
shall endure as the days of trees." Yet the Cedars, 
the "indestructible" Cedars, which once covered and 
were the glory of Mount Lebanon, have all, save a 
very small remnant, disappeared; while the " People" 
that once " filled the land," and, like those " goodly 
cedars" to which they were compared, " sent out their 
boughs unto the sea and their branches unto the river," 
have been driven out and dispersed into all lands, — • 
" scattered and peeled."* — I am, &c. 

* Isaiah xviii. 2 and 7. 



LETTER III. 



" It has often happened to me to have been occupied by a par- 
ticular subject of inquiry ; to have accumulated a store of facts con- 
nected with it ; but to have been able to proceed no further. Then^ 
after an interval of time, without any addition to my stock of know- 
ledge, I have found the obscurity and confusion, in which the subject 
was originally enveloped, to have cleared away ; the facts have 
seemed all to have settled themselves in their right places, and their 
mutual relations to have become apparent, although I have not been 
sensible of having made any distinct effort for that purpose." 

Sir B. C. Brodie, Bart. 

April 18, 1854. 

My Dear Sons, 

1. In my last letter I hope I did not altogether fail 
of my purpose, which was to shew you, that as trees 
are commonly regarded, it is impossible to arrive at 
any satisfactory knowledge either as to their natural 
size or their natural longevity. And I would fain per- 
suade myself that you are now prepared cordially to 
go along with me to the examination of my theory. 

2. Of this theory, I doubt not you still retain a 
general notion. But before entering on the evidence 
to be adduced in support of it, or meeting the objec- 
tions that may be urged against it, it will be desirable 



26 



LETTERS ON TREES. 



to make the theory itself clear and intelligible in all 
its parts. 

3. Agreeably to this theory, as you may remember, 
a tree is not what it is commonly believed, and what 
it certainly appears to be, a single or an individual 
plant. On the contrary, it is a collection— congeries, 
or congregation of individual plants of the same species, 
and is the production of a series of successive years. 
It consists, when fully equipped at midsummer, partly 
of living and growing plants, the growth of the cur- 
rent year, and partly of the persistent dead remains 
of the plants of former years. And of the individual 
plants composing it, each lives only one year, reaches 
its full size within the year, and, on dying at the close 
of it, mostly disappears and passes away. Certain 
parts, however, remain. These are the buds which 
survive the winter, and the dead stems and roots which 
are to serve the purposes as well of a soil as of frame- 
work to the plants of the next and succeeding years. 
And, accordingly, the production of the aggregate, 
which makes up and constitutes the tree, is referable 
to the living plants of each year growing parasitically 
at the end of, and likewise either around or within, 
the dead stems and roots of the plants of the previous 
year. 

4. All this I stated in my first letter. I now advance 
a step further and say, that the theory in question 
forms but a part of a proposition in vegetable physi- 



LETTER III. 



27 



ology of a still more general character, and may be 
more clearly apprehended if this proposition be laid 
alongside of it. The proposition is this : That all 
plants without exception, even those called perennial, 
are strictly annual plants, live therefore only one year, 
and reach their full size within the year ; that is to 
say, that all plants spring up year by year either from 
seeds or buds, and attain their maturity within the 
year, forming, in the course of it, either seeds or buds, 
or both seeds and buds, for the production of similar 
plants the following year ; that, as the season advances, 
their vital actions languish, and their organism becomes 
drier and more rigid — changes these which constitute 
their old age ; that at the close of the season they 
die ; and that on this happening, the materials com- 
posing them speedily undergo either an entire or a 
partial disintegration, — in the one case wholly disap- 
pearing, — in the other, some portion remaining to serve 
ulterior purposes in the vegetable economy of nature, 
but still remaining only as dead vegetable matter. 

5. And in connection with this general proposition, 
and as forming part of it, it may be further stated, 
that the only difference between the plants called 
annual and those called perennial is, that the former 
produce seeds only for the propagation of their species, 
and are reared annually from seeds alone : while the 
latter produce both seeds and buds, and, as perennial, 
spring up each year from buds ; and, therefore, that 



28 



LETTERS ON TREES. 



seeds and buds are in their own essential nature ide7i' 
tical. the onlv difference between them — and that not 
a uniform one — being, that seeds are free, detached, 
isolated, and intended for dispersion — buds fixed and 
adherent to the stem on which they grew. 

6. If now, in regard to any given tree, or kind of 
tree, it be asked, How long does it naturally Uve? " 
the proper answer will be (contrary, however, to the 
common behef ), that there is no set limit to the age it 
may attain, or the number of years it may Uve, and 
no actual limit other than that resulting from purely 
accidental or extraneous causes ; because, according to 
the theory now advanced as to the nature of trees, 
there is no natural Hmit to the annual propagation 
from buds of the individual plants composing the tree. 
According to this view, the observation of Richard 
(formerly quoted) — to wit, that the Cedars of Lebanon 
appear to be ^' indestructible " — is perfectly intelhgible, 
involves no violation of the principle that all living 
beings are subject to the law and the dominion of 
death, and is applicable, besides, to all trees. 

7. And if it be asked, in respect of any given tree, 
" What is the size to which it naturally grows ?" the 
proper answer will be (contrary, again, to the popular 
behef), that there is no determinate hmit thereto, and 
no actual hmit, except from such extrinsic causes as 
may prevent the formation of buds, or the evolution 
from them of new plants. 



LETTER III. 



29 



8. If, however, the Hke questions be asked, not in 
respect of individual trees, but of individual tree- 
plants (as these may well be called) — of the Oak, the 
Elm, the Fir, viewed simply as plants, and inde- 
pendently of their parasitic relations to others of 
their particular species and community, very dif- 
ferent answers must be returned. The answer to the 
first question will be, that they live, one and all of 
them, only a single year ; and that, as regards their 
longevity, they stand on precisely the same footing 
with confessedly annual plants. And in answer to the 
second question, it may always suffice to observe, that 
as they all attain their maturity within the year, so 
the natural size of any of them may be accurately 
determined by observation of the seedling plants of its 
kind in the forester's nursery, or of the yearly shoots 
issuing from the buds on any healthy tree of its kind ; 
and, in general terms, that while subject to some 
variety, it does not in any species exceed a few inches, 
or at the utmost a very few feet, in length. 

9. There are still sundry particulars in this theory 
that require to be more fully unfolded ; but it will be 
convenient to take them up separately. — I am, &c. 



LETTER IV. 



The growth of one year is only subservient to the circulation of 
the next, and is ever afterwards of use merely in giving strength 
and stability to the trunk, in order to support the increasing size 
and weight of the branches and leaves." — Dr John Ware. 

June 30, 1854. 

My Dear Sons, 

1. To proceed with the exposition of my theory. I 
have said that the dead stems and roots of the plants 
of this year serve to the plants of next year both the 
purpose of a soil and the purpose of a support, or of a 
framework, or scaffolding ; that the former is for a 
time only, the latter for all time — the one purpose 
being temporary, the other permanent as the tree 
itself; and likewise, that the living plants of this year 
grow parasitically at the extremities of, and also either 
around or within, the dead stems and roots of the 
plants of last year. Possibly you may have difficulty 
in comprehending what all this means. I will endea- 
vour to make my meaning plain. 

2. Trees, you know, are divided by botanists into 
two great classes, the Exogens and the Endogens. 




P LA N OP Pi R Tr E E 



LETTER IV. 



31 



They speak of trees as being either exogenous or en- 
dogenous, according to the manner of their growth 
and the disposition of their parts. In the first of 
these, as the Greek word from which the name is 
derived signifies, the woody matter yearly added to 
the trunk (or the annual woody layer) grows and is 
deposited outside that of the previous year ; in the 
latter, as the Greek derivation of the name implies, 
the woody matter of the one year is deposited 
inside that of the previous year. The Fir is an 
example of the first, the Palm of the second sort of 
tree. 

3. Let us first of all see how the matter stands in 
respect of the exogen ; and for illustration sake, let us 
take a Fir-tree — the Larch, for example. The engrav- 
ing on the opposite side, entitled " Plan of Fir-tree," 
is an ideal representation of such a tree, — stript of its 
bark, as high nearly as where the branches are seen 
to come off, next sawn crosswise to the centre of 
the trunk, and then cut vertically downwards, right 
through the middle plane of the trunk and roots. It 
exhibits the relations Avhich the several parts com- 
posing the trunk and roots bear to one another. In 
other words, it is a representation of the relations that 
subsist between the organic remains — i. e,, the dead 
stems and roots — of the annual fir-plants that have 
grown successively one above another. To avoid com- 
plexity in the details both here and in the "plan," 



3-2 



LETTERS ON TREES, 



the vertical plants alone are figured — the side plants, 
composing the branches, being supposed not to have 
grown during the first few years.* 

4. In the centre of the trunk, just above the surface 
of the ground, as figured on the plan, is an oblong 
narrow clear space, bounded on every side by a dark 
line of corresponding form, and terminating above in a 
sort of head or tubercle. Directly above this is another 
similar space, bounded by a similar line, and furnished 
with a head or tubercle. And above this again is 
another space exactly resembling the other two, and 
enclosed after the like fashion. These lines, spaces, 
and tubercles, represent respectively a section of the 
woody stems, the medullary (pith) cavities, and the 
buds of the first three in the series of fir-plants. From 
the bottom of the first and undermost, is seen passing 
down into the soil a single dark line : this is the root 
of the first year's plant. From the bottom of the 
second are seen two narrow lines, one on either side, 
also j)assing downwards, — first along the stem, and 
then along the root of the former, — at the extreme 
point of which (below) they meet, and beyond which, 
after meeting, they extend a short way as a single 
line : These denote the root of the second year's plant. 
And so of the third, — the roots of the third year's 
plant passing down alongside first the stem and then 
the root of the second year's plant, meeting at the tip 

* Compare this "plan" with figure 1 (A and B). 



LETTER IV. 



33 



of this root, and thence extending singly still farther 
into the ground. 

5. Ideal as this plan is, the representation given 
tallies very exactly with the appearances presented by 
a young fir-tree cut lengthwise through the middle ; 
and may at any time be verified, as regards the trunk, 
by examining a railway sleeper — at least one that has 
chanced to be suitably sawn. No continuous, uninter- 
rupted, medullary cavity (as many fancy there is), 
reaching from the top to the bottom of the tree, and 
filled with pith, or the remains of pith, will there be 
seen. What we actually find is a set of narrow spaces 
or cavities, rising one above another, in number cor- 
responding to that of the annual shoots (which in fact 
they indicate), each circumscribed and shut off from 
those directly above and below it by a thin layer of 
woody tissue, and each containing a dry cellular sub- 
stance, the remains of the succulent pith with which it 
once was stored, and each varying in length from ten 
inches or less to a foot and a half or more, according 
as the year's growth has been. On either side of 
these medullary cavities may be seen a series of woody 
layers passing downwards in the direction of the 
ground ; their number progressively increasing in that 
direction, and each pair coming off from the lower end 
of each one of those medullary cavities, — each one of 
these, therefore, in succession downwards, having a 
pair more investing it than the one directly above it. 

c 



34 



LETTERS ON TREES. 



And on the summit of the terminal shoot of the tree 
will be found a bud in immediate connection with the 
pith of that shoot, and this pith (if the tree have re- 
cently been felled) plump and succulent. 

6. The longitudinal woody layers then of the trunk, 
though above ground, I have described as being 
(equally with the continuations of them under ground) 
the roots of the several plants that have grown sue* 
cessively one above another. They are not, indeed, 
commonly regarded as roots, but simply as the wood 
and conjointly as forming the trunk of the tree, — the 
term root being restricted to all that part of the tree 
which lies buried in the soil. Believing them, how- 
ever, to be really of the nature of roots, I call them 
such, and their being so regarded forms an integral 
part of my theory. 

7. The persistent stems and roots, then, of the seve- 
ral fir-plants are successively set one above another, 
and alongside of one another, — the stems of the plants 
of one year resting on the stems of the plants of the 
previous year, and their roots creeping down outside 
both the stems and the roots of the latter, and even 
extending beyond. Thus are the parts below a mecha- 
nical support (a framework or scaffolding) to the parts 
above ; while these in their turn become conservative, by 
cutting off from the parts below atmospheric and other 
influences, which would otherwise speedily entail their 
decay. Thus, too, are successive additions made to 



LETTER IV. 



35 



the height and thickness of the aggregate remains of 
the plants ; and thus also, while the roots of the plants 
of each succeeding year, extending beyond those of the 
preceding, strike into new and fresh soil, is the basis 
of sustentation under ground proportionally widened 
and strengthened. Fig. l. 

8. As yet I have said no- B 
thing as to the hark and its 
disposition. A fresh layer of 
this is formed annually in 
connection with the plants of 
each year ; and if our theory 
be correct, the successive an- 
nual layers will be disposed 
in accordance with its re- 
quirements. And such is 
actually the case. The woody 
stem and root of each seed- 
ling tree-plant is everywhere 
invested on its exterior with 
a coating of bark, as in figure 
1, A. But how do the bark 
and root of the next year's 
plant comport themselves in 
relation to the wood and 
bark of this seedling, on the 
summit of which it grows ? 
By the theory they ought to press down wedgewise 



A 



36 



LETTERS ON TREES. 



between them, parting them asunder. And this they 
do, as represented in figure B. And these latter, 
again, in direct relation to one another for one season, 
are themselves in their turn parted after the like 
fashion by the root and bark of the third year's plant. 
And so on. Thus, the most external of the annual 
layers of bark corresponds to the most internal of the 
annual layers of wood. And were the several layers 
of bark distinguishable, or rather could they be sepa- 
rated from one another, each would be found to cor- 
respond in length with the plant in connection with 
which it grew, and the whole to become individually 
longer from without inwards, as shewn in figure C. 

9. From this disposition and wedgelike action of the 
wood and bark, it comes to pass that year by year the 
older layers of wood are pressed inwards, and more 
closely compacted ; while the older layers of bark are 
pushed outwards, and become in process of time so 
distended or stretched, that, unable to yield otherwise 
to the pressure from within, they rend. And this 
occurs in a great variety of ways — by exfoliation in 
some (as in the Sycamore or Plane, and in the Birch),, 
and by fissure in most (as in the Fir, the Oak, and 
very remarkably in the Acacia) — each particular kind 
of tree having its own, and, it may be added, its dis- 
tinctive manner of rending. 

10. Again : The bud at the top of the terminal 
shoot, the embryo of the plant of next year, is to 



LETTER IV. 



37 



derive the first materials for its development in spring 
from the succulent pith of that shoot. This pith is 
simply a store of nourishment laid up in the cells, 
which fill the medullary cavity of the shoot ; and it is 
placed in closest proximity to the bud for the supply 
of its earliest and more immediate wants. Thus the 
shoot or stem yielding nourishment to the bud (besides 
being to it, as we have seen, a stand or support on 
which and around which to grow), may fairly be said 
to serve to the young plant, which is to emanate from 
the bud, the purpose of a temporary soil. This pur- 
pose answered, and the supply of nourishment there 
exhausted, the growing plant issuing from the bud will 
send down a root ; and this root, passing alongside the 
stem and the root of the plant of the bygone year, will 
ultimately reach the ground. In its course down- 
wards, encased in its own layer of bark, it will pass 
between and part asunder the bark and the woody 
tissue of the stem and root of that plant, traversing 
in its passage the cellular tissue which connected these, 
and which, stored with nutritious juices as the pith 
was, will supply all its intermediate wants. On reach- 
ing the ground — its permanent soil — it will thence 
derive what further supplies it needs. 

11. I have repeatedly spoken of the roots as creep- 
ing down, and as passing from the lower end of the 
stems of the plants above downwards, into the soil. I 
use this expression meanwhile analogically and pro- 



LETTERS ON TREES. 



visionally. The fibres composing the roots do creep 
down virtually, although not actually, — potentially and 
in effect, but not really. And I shall continue to make 
use of these expressions till such time as I explain how 
the roots are in fact evolved. I am, &c. 



LETTER V. 



Look here, upon this picture." — Hamlet. 

August 18, 1854. 

My Dear Sons, 

1. Hitherto we have examined the Exogen in its 
longitudinal or vertical aspect only. Let us now view 
it in its transverse or horizontal, and in connection 

^^yith a tissue which is equally annual in its formation 
as the wood or bark, but widely different from the 
former, at least in the manner of its disposition and 
growth. I mean the cellular tissue. This tissue may 
be said to be the basis or matrix within which, or 
rather through the midst of which the bundles of 
woody tissue pass, and by means of which they are 
bound and knit together^ The medullary rays, as 
they are called, seen in *the cross-cutting of a tree, 
have their seat in this cellular tissue, and are in fact 
nothing save a peculiar appearance given to it by the 
mode in which the bundles traverse it. 

2. Viewed in this aspect, the additional facts fur- 
nished by the Exogen will, if I mistake not, come out 

\ very favourably for our theory. 



38 



LETTERS ON TREES. 



yisionally. The fibres composing the roots do creep 
down virtually, although not actually, — potentially and 
in effect, but not reallv. And I shall continue to make 
use of these expressions till such time as I explain how 
the roots are in fact evolyed. I am, &c. 



LETTER V. 



Look here, upon this picture." — Hamlet. 

August 18, 1854. 

My Dear Sons, 

1. Hitherto we have examined the Exogen in its 
longitudinal or vertical aspect only. Let us now view 
it in its transverse or horizontal, and in connection 
with a tissue which is equally annual in its formation 
as the wood or bark, but widely different from the 
former, at least in the manner of its disposition and 
growth. I mean the cellular tissue. This tissue may 
be said to be the basis or matrix within which, or 
rather through the midst of which the bundles of 
woody tissue pass, and by means of which they are 
bound and knit together^ The medullary rays, as 
they are called, seen in the cross-cutting of a tree, 
have their seat in this cellular tissue, and are in fact 
nothing save a peculiar appearance given to it by the 
mode in which the bundles traverse it. 

2. Viewed in this aspect, the additional facts fur- 
nished by the Exogen will, if I mistake not, come out 

\ very favourably for our theory. 



40 



LETTEKS ON TREES. 



3. The accompanying figures are plans of hori- 
zontal sections of the stems of Exogens, and shew the 
wood, the bark, and the cellular tissue, together with 
the central medullary (or pith) cavity and the medul- 
lary rays. Figure 2 is the 




scheme of a shoot one vear old. 
In the centre (a) is the medul- 
lary or pith cavity ; around this 
are blocks or bundles of woody 
fibres (cZ d d), having the appear- 
ance of truncated wedges, and 
forming the woody stem of the 



shoot. Proceeding from the me- 
dullary cavity, and passing between the bundles (which 
they separate and isolate), are the medullary rays 
(c c c) : encircling both these and the bundles is a ring 
of cellular tissue (b h b), which may be termed the 
medullary ring ; and encircling the whole is the bark 
(eee e). The medullary cavity, the medullary rays, 
and the medullary ring, are everywhere continuous, 
form but one and the self-same tissue — the cellular, 
and have their distinctive appearances given them 
simply by the woody bundles passing down through the 
common mass of tissue. Take away these bundles, and 
nothing will appear save an unbroken mass of cellular 
tissue, enclosed within a ring of bark. 

4. This cellular tissue, which, as I before remarked, 
appears to be the basis or matrix of the whole stem or 



LETTER V. 



41 



shoot, grows and extends itself horizontally. In the 
course of each season provision is made for that which 
is to be developed the next, just as provision is made 
for the evolution of every part of the new plants. 
That is to say, equally with a set of buds, a layer of 
embryo cellular tissue is each year produced for the 
purposes of the next. This layer has received the 
name of Cambium^ and is found on the side of the 
medullary ring next the bark. On the return of 
spring it begins to grow, and rapidly extends itself by 
the development of new cells. These in due time are 
traversed by a new set of 
woody bundles {a a a) as 
represented in figure 3. 
These bundles are the roots 
of the new plants emanating 
from the buds, and they 
pass down in such manner 
as that the new medullary 
rays are on a line with those 
of last year's. The whole is 
bounded by a new layer of bark {h b 6), lying inside 
that of the previous year's plant. And it may be 
remarked in passing, that, while the cellular tissue 
serves permanently to bind those woody bundles or 
roots together, it serves to them also, in their passage 
to the soil, the like office which the pith in the medul- 
lary cavity does to the bud — that of supplying their 
present needs in respect of nourishment. 




42 



LETTERS ON TREES. 



5. The only difference between that part of the 
stem which is above ground and that 
which is below, consists in the absence 
from the latter (as shewn in fig. 4), of 
the central medullary cavity. The 
woody bundles here have still the 
common cellular tissue for their basis, 
and the medullary ring and medul- 
lary rays exist as in that portion of it which is above- 
ground; but the bundles meet at a point in the centre. 
There being no buds on this central portion of the root, 
to be nourished by it (although, as we shall hereafter 
see, there often is on its exterior, lying underneath 
the bark, and in connection with the medullary ring), 
the pith and its containing cavity are wanting. 

6. The disposition of the woody bundles in concen- 
tric zones or circles, is by no means always so regular 
as is represented in the foregoing figures. In the Fir, 
indeed, as associated with other firs in a close planta- 
tion, and growing chiefly in the vertical direction 
(the lateral branches or side plants being, from the 
circumstance of their position, arrested in their 
growth), the disposition is, on the whole, singularly 
uniform. In most trees, however, and, in fact, in all 
that have full freedom of growth allowed them, not 
only do the zones of different years vary greatly in 
thickness, but different parts of the zone of the same 
year are very unequal in this respect, as shewn in 




LETTER V. 



43 



figure 5. Hence the central point of the trunk is by 
no means always the medullary cavity, which is con- 
sequently more Fig. 5.*^- 
or \es^ eccentric. 
How is this? 
These zones are 
sections of the 

roots of the , / y - „ . 

plants above, 
and their thick- ' ' ' 

ness indicates , ; . _J 

the quantity of ' ^ 

roots sent down, i . , ' 

which will of ^j-' ' 

course be in pro- ^^ ' 

portion to the \^ f 
number of the ^ _ \ / ^ 

plants, and the "^-- --^-.=^555^^^ 

vigour of their growth. In these respects there are 
great differences in different years and on different sides 
of the tree, corresponding to variations in the tempera- 
ture and character of different seasons, and likewise to 
variations in respect of exposure to light, to prevaiHng 
winds, and other causes. That is the explanation.f 

* Fig. 5. Concentric woody circles of the Box-tree, — from the 
drawing made by Nature on the block from which it is printed. 

t " In a crowded plantation there is a marked difference between 
the trees on the outside and those in the centre ; the former, having 



44 



LETTERS ON TREES. 



7. An extreme degree of this — natural, seemingly, 

to several sorts of trees, particularly the Beech, the 

Yew, the Thorn, and the Normandy Poplar — consists 

in sets of woody bundles (such as those connected 

with particular branches) grouping themselves toge- 

^ ^ ther year after 

Fig. 6.* 

year, to the ex- 
clusion of other 
bundles, and pass- 
ing; down in masses 
more or less dis- 
tinct (Fig. 6). 
The trunk has thus 
given to it a colum- 
nar or buttressed 
aspect; and a sec- 
tion of it, while exhibiting often great confusion in 
the mutual relations of the zones and the cellular 
tissue, shows, even more clearly than can be made out 
from an inspection of the exterior of the trunk, both 
the extent and the reality of the grouping. This 
arrangement, you cannot fail to perceive, is in prin- 

tlieir branches and leaves fully exposed on one side, grow with com- 
parative vigour, and form excellent timber on that side of the stem 
where light and air are admitted ; while the latter, hemmed in on 
all sides, are drawn up like bare poles, producing a small amount of 
ill-conditioned wood." — Balfour's Class-Book of Botany, p. 428. 

^ Fig. 6, Section of stem of a tropical Climbing -tree, copied from 
the English Encyclopcedia, art. Exogens. 




LETTER V. 



45 



ciple — nay. is in fact, that which obtains in a still 
greater degree in all trees as soon as the woody bundles 
reach the soil. At this point the bundles not only 
group themselves into sets, but part company alto- 
gether, spreading themselves in all directions in the 
ground. Need I say how strikingly this process of 
grouping identifies the bundles above ground with 
those under ground, and imparts to both one common 
character.* 

8. One other feature the bundles often present, allied 
to that just mentioned, and not less remarkable in the 

^ The following passages from Wallace's Travels on the Amazon 
(p. 23) furnish an admirable illustration of the statements in the 
text : — " Among the trees, the various kinds that have buttresses 
projecting around their base are the most striking and peculiar. 
Some of these buttresses are much longer than they are high, spring- 
ing from a distance of eight or ten feet from the base, and reaching 
only four or five feet high on the trunk ; while others rise to the 
height of twenty or thirty feet, and can even be distinguished as 
ribs on the stem to forty or fifty. They are complete wooden walls, 
from six inches to a foot thick, sometimes branching into two or 
three, and extending straight out to such a distance as to afPord 
room for a comfortable hut in the angle between them. 

Other trees, again, appear as if they were formed by a number 
of slender stems growing togetlier. They are deeply furrowed and 
ribbed for their whole height, and in places these furrows reach 
quite through them, like v^ndows in a narrow tower ; yet they run 
up as high as the loftiest trees of the forest, with a straight stem of 
uniform diameter. Another most curious form is presented by those 
which have many of their roots high above the surface of the ground, 
appearing to stand on many legs, and often forming archways large 
enough for a man to walk beneath." 



46 



LETTERS ON TREES. 



like point of view. It is this : very often, instead of 
passing down in straight Hnes, they wind about the 
trunk, turning and twisting themselves, in their course 
downwards, in an endless variety of ways. Particular 
fibres or bundles, or sets of these, which, eight or ten 
feet up the trunk, may be distinctly seen on one side 
of it, perhaps forming part of a branch on this side, 
may be traced gradually making their way round to 
the opposite side, and in the end joining one of the 
roots under-ground, which spreads itself in this other 
direction. Even Avhere their course is, on the whole, 
in a tolerably perpendicular direction, their meander- 
ings are frequently singular enough — the fibres occa- 
sionally reversing their course, and after a little space, 
turning sharply round again, going out of their pro- 
per direction (as if actuated by a sort of instinct) to 
avoid obstacles, and then holding on their way. The 
old Yew in Pear-tree Green Churchyard, and the 
magnificent Chesnut in North Stoneham Park, afi'ord 
excellent illustrations of these particulars. But an 
inspection, in any timber-merchant's wood-yard, of the 
pieces of hard-wood that have been stript of their 
bark — and particularly of those parts of them where 
the chief branches join the trunk — will illustrate them 
sufficiently well. 

9. One other observation, and I will bring this let- 
ter to a close. There may be said to be a certain 
antagonism between the woody and the cellular tissue. 




Elm at North Stoneham, Hants, with Roots riLLiNG up the Decayed Bole. 



LETTER V. 



# 47 



One main use of the cellular tissue is to bind together 
the woody fibres, as well as all the other parts of the 
plant. Its tendency, accordingly, is of a cohesive 
nature. The tendency of the woody fibres, on the 
other hand, at least as they exist in the roots," is 
to separate from one another, to strike off sideways, 
and spread themselves horizontally in all directions. 
And this tendency is exhibited in not a few trees (as 
we have just seen), even in the fibres composing the 
trunk. To what cause this tendency is more imme- 
diately owing, we need not now inquire ; but in as far 
as it is not actively exerted, in so far do the fibres 
glide passively down, as in a mould, between the last 
year's layers of wood and bark, and yield themselves 
to the agency of the cellular tissue. Thus is their 
real character as roots overlaid and obscured in the 
trunk. Break down that mould, however ; take away 
the cellular tissue, and the fibres will stand out even 
in the trunk as genuine roots. Do you ask for a 
proof of this assertion ? You have it in the Elm at 
North Stoneham in this vicinity, of which I give you 
a representation on the opposite page. It had been 
dismembered, many years ago, of one of its chief 
limbs, which had at the same time, in parting, 
riven and splintered a large portion of the bole, 
destroying also the cellular tissue there. Since then 
the woody fibres have continued year by year to 
pass down from the living and growing parts above. 



48 



LETTERS ON TREES. 



Reaching the injured part of the trunk, they have 
then found themselves naked and exposed, unsup- 
ported, and unfettered also, by the cellular tissue ; 
and thus circumstanced they have gathered round 
them, each fibre for itself, or each little bundle for 
itself, a thin coating of bark, and still pushing on, 
some in mid-air, and some on broken pieces of the 
trunk, have become and do now display themselves as 
genuine and unmistakeable roots. Nor is it uninter- 
esting to remark that the splintered wood, exposed for 
many years to the full action of the weather, has 
rotted; and that (soft, spongy, and friable) it has in the 
course of time come to be mixed up with earth, wafted 
to it as dust from the adjoining fields and road, 
and so has formed a veritable soil everywhere per- 
vaded by those roots. I am, &c. 



LETTER VI. 



« It is pleasant to note all plants, from the rush to the spreading cedar, 
From the giant king of pahns, to the Uchen that staineth its stem.*' 

Martin Farquhar Tupper. 

September 20, 1854. 

My Dear Sons, 

1. We have yet to examine the Eadogenous tree, of 
which the Palm is an 
example, and see whe- 
ther the disposition of its 
living parts and of its 
organic remains accords 
with our theorv. I have 
no misgivings as to the 
issue, and am persuaded 
you will agree with me 
in thinking that the whole 

economy of this division 
«/ 

of the Tree-tribe is in 
perfect harmony with 
the theory. 

2. The Palm is, in fact, 
strictly an annual, and 
its evolution year by year 
takes place on this wise : 
In the centre of a whorl 




D 



50 



LETTERS ON TREES. 



of dead leaves is a bud — a truncate flesh-like substance, 
resembling the root-plate of a bulb, but of nearly the 
full size of the after-diameter of the tree on the sum- 
mit of which it rests. This bud, formed by the plant of 
the previous year, and consisting mostly of a mass of 
cellular tissue, first sends out from its exterior a tuft of 
fresh leaves, and then extends itself a short way hori- 
zontally. Next, it rises slowly upwards, leaving the tuft 
of leaves at its base, but giving off others in succession 
from its sides and summit. The leaves in their turn 
send down bundles of woody tissue, which traverse 
the cellular tissue, and, proceeding some distance down 
the tree, finally curve outwards, and lose themselves 
in the cortical integument of its trunk, immediately 
within which (contrary to what obtains in the Exogen) 
the most compact wood is always found. These 
bundles are the roots of the plants ; and these, together 
with the cellular tissue and the persistent remains of 

the first set of leaves (which decay 
and drop off in the course of the 
season), are all that can be re- 
garded as the stem of the plant, 
— for, in reality, according to 
Botanists, it has no proper stem. 
And this stem, such as it is, to- 
gether with those of the plants of 
former years, constitute the trimk of the Palm-tree. 
In figure 8 is represented a transverse section of this 




LETTER yi. 



51 



trunk. It will be seen that there is an entire absence of 
the concentric circles both of wood and bark so charac- 
teristic of the Exogenous stem, and that instead of this 
there is a mass of cellular tissue inclosed within a single 
cortical ring of somewhat irre- 
gular outline, and pierced here 
and there throughout, but most 
abundantly towards the circum- 
ference, by bundles of woody 
fibre. Fig. 9 is a mere plan^^--- 
of the upper part of the palm- ^ 
trunk, showing the manner in 
which the woody fibres pass 
downwards from the leaves in 
curves or arches towards the 
circumference of the stem, in 
the cortical integument of which 
they lose themselves. 

3. The trunk of the Palm-tree, it may be observed, 
does not increase in diameter by age, as does that of 
the Exogen. It increases only in height, and that by 

* Fig. 9. — a h, The lower, fully developed, part of the stem; c c,- 
External firmer portion of the stem, formed by the closer course of 
the woody fibres ; d d d, Woody fibres running as far as the cica- 
trices of leaves that have died ofp; e e e e e, Leaves in the bud, in 
the order in which they are developed, with the woody fibres belong- 
ing to them ; / /, The latest-formed leaves. All that is cut off by 
the dotted line oc y, above the stem, has originated at the same time 
with the lowest pair of leaves (e e). — See Schleiden's Principles of 
Scientific Botan'^, p. 246. 




52 



LETTERS ON TREES. 



reason of the successive production of distinct palm 
plants growing year after year one above another. In 
most species of Palm there are no branches. In most 
the trunk towers upwards singly and alone, — some- 
times to an elevation of 150 or 180 feet, and is naked 
throughout, save only at the summit, where it is sur- 
mounted with large and numerous leaves, with flowers 
and fruit ; and likewise, in the very centre, and form- 
ing its highest point, with a fleshy bulb or bud for 
the evolution of next year's palm plant. This trunk, 
in fact, may not inaptly be likened to a stately monu- 
mental column, on the top of which an embryo palm 
plant is every year placed by the hand of Nature, — 
the column itself, however, serving to this plant simply 
the purpose of a stand-point, and having as little to do 
with its germination and growth as it manifestly would 
have nothing, were it the " Monument" in Fish Street 
Its offices are purely mechanical, not vital. It gives 
support to the young plants ; and by the porosity of 
its substance, it gives scope for the roots to strike a 
short way down into it, while it also allows fluids to 
pass upwards from the earth beneath for the growth 
and nourishment of the plant. 

4. The trunk of the Palm-tree is fixed to the soil by 
means of a strictly fibrous root resembHng that of the 
grasses ; and this root appears to be derived from the 
woody bundles of the earHest set of plants, — those of 
the plants subsequently formed never reaching the 



LETTER VI. 



53 



Fig. 10. 



ground. It is singular enough, however, although 
quite in keeping with the account now given of the 
Endogen, that in some sorts of Palms, as in the Pan- 
danus^ or Screw Pine (Figure 10), those bundles 
pierce through the trunk, 
and become in the first in- 
stance aerial roots ; and that 
gradually pushing down into 
the ground, apart and at 
some little distance from the 
trunk, they form props or 
buttresses for its support. 

5. The fibres constituting 
the roots of the individual 
palm-plants undergo, I be- 
lieve, no increase in length 
or thickness after the year 
they are formed ; and as 
those which pass into the 
ground proceed from a few 
only of the earliest in the 
series, the hold which the 

trunk of the Palm-tree has of the soil, when compared 
with the height of the column, comes after a time to 
be comparatively slight. I am, &c. 




LETTER VII. 



*^ He was not of an age, but for all time." 

Ben Jonson. 

« To Time 
The task was left to whittle thee away 
With his sly scythe, whose ever-nibbling edge, 
Noiseless, an atom and an atom more 
Disjoining from the rest, has, unobserved, 
Achieved a labour, which had far and wide. 
By man performed, made all the forest ring." 

William Cowper. 

October 21, 1854. 

My Dear Sons, 

1. In a former letter (Letter II.) I told you that in 
different parts of the world there are trees of almost 
all sorts which have already stood for ages, and have 
grown to a vast size ; that many of these trees are 
still vigorous and growing ; and, what is particularly 
remarkable, that they exhibit as yet no signs of what 
can properly be regarded as old age. Much of their 
trunk, as I then remarked, may have been hollowed 
out from the decay of the heart-wood, and many of 
their larger branches may have been broken off in 
the lapse of time. But so much of them as yet remains 



LETTER VII. 



65 



evinces as great activity in the vital processes as ever 
— that is to say, is every year the seat of as energetic 
a circulation of sap ; puts forth every year, and 
matures, leaves and buds, and flowers and fruit, as 
large and perfect as in its earliest years ; and every 
year, notwithstanding the dropping off and destruction 
of its dead parts, is having additional bulk given to it. 
And I instanced, in illustration of all this, the Oak of 
Allonville, the hollow trunk of which has been a little 
paved chapel these hundred and fifty years or more, 
and which, although now from 800 to 900 years old, 
is still vigorous, and still bears abundance of acorns. 

2. This general fact I then adduced as an argument 
against the old theory of trees. I now adduce it as 
an argument in favour of mine. Before proceeding^ 
however, to the proof and vindication of this theory, I 
purpose dwelling for a little on the history of some of 
those reliques of bygone ages, and submitting to you 
some further observations on trees, with a view to the 
introduction of certain details still needed to make the 
exposition of the theory complete. 

3. Of old trees still extant in this country, and still 
living and growing, we need not look beyond the Tew 
tribe. There are indeed Oaks, Limes, Sycamores, 
Chesnuts, Ashes, and others, of great antiquity and 
vast size, some of them coeval with the Conquest, some 
of them probably much older still ; but they all sink 
into insignificance before the Yews. Of these, there 



56 



LETTERS ON TREES. 



are some at Fountain's Abbey, near Ripon, in York- 
shire, which are behoved to be more than 1200 years 
old ; there are two in the Churchyard of Crowhurst, 
in Surrey, 1450 ; and one at Fortingall, in Perthshire, 
from 2500 to 2600 years old. One in Brabourn 
Churchyard, in Kent, is said to have attained the age 
of 3000 years ; and another at Hedsor, in Bucks, 
which is still in full vigour, and measures above 27 
feet in diameter, is reckoned to be above 3200 years 
old. These estimates, indeed, founded on data sup- 
phed by De Candole, are probably too high — the 
Yews in this country being, it is now suspected, less 
slow in their growth than those on the Continent, at 
least than those examined by that distinguished phy- 
siologist. Making due allowance for this, however, 
there can be no question that the Yews just referred 
to have attained to an age that is altogether wonderful. 

4. For details regarding these and other remarkable 
trees in this country — remarkable, I mean, in respect 
of their age and size — I must content myself with 
referring you to the writings of Gilpin, Evelyn, Jesse, 
and others. The subject is too extensive for my limits, 
and would, if entered on at any length, keep us too 
long away from the proper subject of these letters. I 
shall therefore confine myself to a brief notice of three 
or four trees only, the produce of other countries, and 
either not generally known, or peculiarly well fitted 
to serve the purpose I have in view. 



LETTER VII. 



57 



5. In the Brazils, in one of the primaBval forests, 
there are some trees supposed to be Courbarilsy which, 
in respect of size, are truly collossal, and, in respect 
of age, have been variously computed at from 2000 
to 4000 years. " JN'ever before (says Martins) had I 
beheld such enormous trunks. They looked more like 
living rocks than trees ; for it was only on the pinnacle 
of their bare and naked bark that foliage could be 
discovered, and that at such a distance from the eye 
that the form of the leaves could not be made out." 
Fifteen Indians, with outstretched arms, could only 
just embrace one of them. At the bottom they were 
eighty-four feet in circumference, and sixty feet where 
the boles became cyhndrical.* 

6. Another tree which has recently been described 
in certain of the American journals is too remarkable 
to be passed over. It is a Cedar^ growing in one of 
the valleys in the county of Calaveras, in Cahfornia. 

Level with the ground, its circumference is ninety- 
two feet ; at a height of four feet, it is eighty-eight 
feet ; at fourteen feet, it is sixty-four feet, and so i^ 
gradually diminishes. Its height is 285 feet. There 
is nothing misshapen about it. On the contrary, from 
top to bottom, it is a model of symmetry, elegance and 
grace appearing to be conditions of its greatness, and 
its collossal proportions only awakening in the spectator 
ideas of the subhme and the majestic. The age of this 
* The Gardener's Chronicle for January 25, 1845. 



58 



LETTERS ON TREES. 



giant, calculated by its rings, is 2520 years. This king 
of the forest is to be girdled, and the operation has 
already commenced. The bark — which at the foot is 
nearly fourteen inches thick — is to be taken off in 
fragments up to the height of fifty feet, and sent to 
the Universal Exhibition in New York." * 

7. Then there is the famous Boabab (the Adansonia 
digitata) growing in Senegal, and supposed to be the 
oldest kind of tree in any part of the world. The 
trunk of this extraordinary tree does not attain a height 
much exceeding fifteen feet, but in some instances it is 
from eighty to ninety feet in girth. And, according 
to the estimate of Adanson, founded on a comparison 
of Thevet's account of one seen by the latter in the 
year 1555, with his own measurement of the same tree 
two hundred years later, the trees that are twenty- 
seven feet in diameter have an age of 4280 years. 
Some of them have a diameter of thirty feet, and these 
are supposed to have attained an age little short of 
6000 years. 

8. Coeval probably with the Boabab is the Gum- 
Dragon Tree {Dracoena Draco), which furnishes the 
astringent resin called dragon's blood, once used in 
medicine, but now chiefly by painters as a red varnish. 
Of this tree there are two specimens in the Palm- 

* Communicated to the Heraldo " of Sonora, by a correspondent 
'^who lately went to see this prodigy of the vegetable kingdom." — 
Aberdeen Herald newspaper, 1853-4. 



LETTER YII. 



69 



house of the Kew Gardens. Lofty as these specimens 
are (says Sir William Hooker), they are pigmies com- 
pared with the stature the tree attains in its natiye 
island, Teneriffe." One growing there is described by 
Humboldt as the gigantic tree of Orotava" — cen- 
turies ago an object of veneration to the Guanchos 
(the aborigines of Teneriffe). A little above ground it 
measures forty-five* feet in circumference, a girth in- 
deed which, vast as it is, comes far short of that of the 
Boabab. The tree, however, seems to be of exceedingly 
slow growth ; so much so, that according to the tradi- 
tions of it which have been handed down, it was as large 
and hollow 450 years ago as it is now. Sir William 
Hooker observes regarding it, that it is of "incal- 
culable " age. " Doubtless it and the Boabab (he 
adds) are among the oldest vegetable inhabitants of 
our planet." I 

9. The Taxodium Distichum (or deciduous Cypress) 
seems to be the most gigantic of any on record, and 
to be second to none in age. Two existing specimens 
may be referred to — one in the church-yard of Santa 
Maria de Telsa, near Oaxaca, in Mexico, which has a 
trunk ninety-three feet in girth; the other, that of 
Chapultepec, which is said to have a circumference of 
117 feet 10 inches ! Regarded as of wondrous " 
magnitude by the Spanish conquerors, this tree of 

* Professor Balfour says seventy feet (Letter ii. 5.) 
t Popular Guide to the Kew Gardens, 



60 



LETTERS ON TREES. 



Chapultepec certainly " reaches back (according to 
De Candole) to the origin of the present state of the 
world " — an epoch of which (in his view) it is the 
most indisputable monument." Professor Henslow, it 
may be observed, estimates the longevity of the Taxo- 
dium at above 4000 years.* 

10. The Banyan of the East, the Ficiis Indica, is 
also remarkable for its size and longevity. It has 
besides certain peculiarities in its manner of growth 
and extension which demand for it a special notice. 
Every branch, issuing from the main or primary trunk, 
throws out aerial roots, in the form of small tender 
fibres, which gradually elongate and become thicker, 
and at length, reaching the surface of the ground, 
strike into the soil. They gradually increase in girth 
till they form large and distinct trunks. These 
secondary trunks in their turn send out branches 
from the top, which in time give off aerial roots that 
grow downwards into the ground, and become trunks 
also. The tree thus continues to progress, and inde- 
finitely to extend itself. One such tree, now growing 
on an island in the river JSTerbudda, is believed to be 
identical with one that existed there in the time of 
Alexander the Great, and which, according to Near- 
chus, was, even in those days, capable of overshadowing 
10,000 men. It is not now, indeed, so large as for- 
merly, portions of it having been carried away by 
* Sheppard on Trees, their Uses and Biography, p. 89. 



LETTER VII. 



61 



floods. What remains, however, affords ample room 
for 7000 persons to repose under its shade, and has a 
circumference of 2000 feet — measuring, that is to say, 
round the principal trunks. The overhanging branches 
cover a much larger space. The chief trunks of this 
single tree, it may be added, greatly exceed in thick- 
ness our English Oaks and Elms, and are above 350 
in number, while the smaller trunks number more 
than 3000 ; — and every stem is still becoming thicker, 
and still sending out new branches and hanging roots, 

11. As directly akin to the subject before us, I 
cannot forbear directing your attention to an enormous 
plank^ which was some little time ago to be seen at the 
Bridgewater Canal Yard, Chester Eoad, Manchester ; 
and wliich had been brought there from Liverpool by 
the Canal. Its dimensions were — length, 144 feet ; 
breadth, twenty inches ; and thickness, six inches 
throughout. It was of a species of wood known as 
gum-wood, or African Oak, and was imported from 
Africa into Liverpool during last summer (1851). The 
tree from which this plank had been sawn must have 
been of a gigantic height, probably not much less than 
300 feet.* Its age must have been proportionately 
great. 

12. Let these examples suffice.f Enough appears 

* The Gardener's Chronicle for July 17, 1852. 
t One other may be referred to here. At the floral exhibition 
held in the Crystal Palace, on Saturday, June 2, 1855, there was to 



62 



LETTERS ON TREES. 



from them to shew that trees may attain to an age 
altogether wonderful, and to a size that is quite prodi- 
gious, ayid still continue to live and grow. 

13. But you may very naturally remark, that, after 
all, as common observation demonstrates, the indi- 
vidual instances of trees of such extraordinary growth 
and longevity are comparatively — indeed, actually- 
very few ; and that, if the representation I have given 
of the nature and constitution of trees were well- 
founded, they should be very numerous. Nay, you 
may ask how it comes, that we nowhere find what we 
might expect to see everywhere, Oaks, Elms, Firs, 
and others of our famiUar forest-trees, evincing by 
their size and by their appearance generally, that 
they are coeval with the creation of man — coeval at 
least with the Deluge, or the age immediately suc- 
ceeding that catastrophe ? 

14. Allowing freely that none such exist anywhere 
on the earth's surface, unless, indeed, we may except 
the Boahah, the Draccena, and the Taxodium, said 
to be severally from 4000 to 6000 years old, — and 
readily admitting that trees of any kind much exceed- 
ing even a few centuries are extremely rare, the 
answer to these questions is not far to seek. All 

be seen, among the curiosities of the show, in a moderate-sized 
flower-pot, a specimen of the Wellingtonia gigantia — "the parent 
tree of which, we are told, was 300 feet high, thirty feet in diameter, 
and supposed to be 3000 years old." — The Times Newspaper, June 
4, 1855. 



LETTER VII. 



63 



trees, and some kinds more than others, are subject to 
certain influences from without, and to certain changes 
from within, which unfaihngly entail, not the natural 
decline and death, but the accidental destruction of 
the far greater number of them, — and that before the 
lapse of any very lengthened period. In Endo- 
genous trees, for example, the trunk, incapable of 
yielding sideways, has, after a time, its interior so 
thoroughly filled up below with the roots of the plants 
above, that the sap can no longer ascend ; whereupon 
either the last-growing plant dies, or the bud of the 
next in succession is not developed. A change some- 
what similar, and attended with the like result, appears 
to occur in old trees of the Exogenous kind. The 
internal and more recently formed layers of bark are 
prevented from yielding by the drying and hardening 
of the older layers of bark without ; while the inner 
and older wood loses its porosity, partly by the pres- 
sure of the younger wood without, and partly from 
deposits {crystalline?) of organic matter in its sub- 
stance. And thus it happens that neither can the 
roots of the growing plants readily find room to grow, 
nor can the sap rise freely upwards. Again, in Endo- 
gens, the trunk becomes at length so disproportionate 
in height to the naturally narrow basis of sustentation 
under ground, as to be easily blown down. And even 
in Exogens, proportionally broad as this basis is, the 
vast height and breadth of surface which they at 



64 



LETTERS ON TREES. 



length acquire, causes the wind to act on them to their 
destruction, the older they become, at an advantage 
infinitely greater than in their earher years. 

15. Further, all dead organic matter sooner or later 
undergoes certain purely chemical changes, which lead 
to its decay or decomposition, and end in its disap- 
pearance ; and this process once begun goes on all the 
more rapidly that the conditions favourable to it obtain. 
I need scarcely remind you that, according to the 
theory, the greater part of all trees consists of vege- 
table tissue that has lost its vitality ; and it must be 
obvious to you, that exposed as they are to the full 
action of the weather, trees are naturally placed in 
circumstances highly conducive to the decay of this 
tissue. Endogens, indeed, are for the most part swept 
away or otherwise destroyed before there is time for 
the occurrence of such decay. But in Exogens, the 
process is matter of daily observation, while its results 
are familiar to every one. From this cause, the heart- 
wood of all of them after a time disappears, leaving 
the trunk hollow within, often reducing it to a mere 
shell, and thus necessarily weakening the mechanical 
support given by it to the growing parts above, as 
well as its power of resistance. And it is obvious to 
remark, that the older an Exogen becomes, its liability 
to be uprooted or dismembered by any passing storm 
of wind, increases in a double ratio, and from two dis- 
tinct but concurring causes, — on the one hand (in sum- 



LETTER VII. 



65 



mer especially, when in full leaf), from its greater size 
and breadth, enhancing the power of the wind, — and, 
on the other, from the more extensive decay of the 
heart-wood, making it less able to withstand the agency 
of the wind. 

16. Moreover, the nourishment existing in the soil 
comes often to be exhausted, and even that supplied 
by the atmosphere to be rendered unavailable. Of 
this, plantations furnish us with continual examples. 
The forester or the wood-merchant may tell us that 
certain sorts of trees become ripe " after seventy, 
eighty, or ninety years, and after that do no more 
good. They thus speak of trees growing together in 
a wood — of Firs, for example. So far, or in a certain 
sense, they speak truly. And the explanation of the 
thing is, that the trees so circumstanced have by that 
time extracted from the soil all the nutriment it can 
yield them, and particularly the saline matters (ashes) 
that are essential to their growth. And you must 
yourselves have often noticed (in plantations especially 
that are densely crowded, and have not been duly 
thinned), that such trees are wholly, or at least almost 
quite destitute of branches, — the side plants, that is 
to say, having either been stunted in their growth, or 
having altogether died out. And this happens, because, 
although the air (from the carbonic acid of which they 
derive a large part of their nourishment), can gain 
access to them, the light and the heat of the sun, with- 

E 



66 



LETTERS ON TREES. 



out which it is impossible for them to appropriate it, 
cannot reach them. And yet the same sort of trees, 
growing singly or at suitable distances, freely exposed 
on all sides to light, heat, and air, — and having, besides, 
an unhmited command of fertile soil, may flourish for 
centuries, spreading abroad numerous and massive 
branches. In proof and illustration of this, let me 
refer you to the condition of any ordinary plantation 
of Larches seventy years old, as compared with that 
of the two Larches in the Park at Dunkeld, in Perth- 
shire — the first of the kind introduced into this country, 
and planted by the Duke of Athole in 1737. The 
former are tall, straight, branchless poles, growing only 
at the top, their growth even there failing, and likely 
soon to cease entirely : the latter tall also, but thick 
in proportion, and amply furnished with large and 
spreading branches, growing in all directions, and alto- 
gether presenting such an aspect as bespeaks for them 
a much more prolonged existence, and a much greater 
height, and breadth, and girth, than they have yet 
attained.* 

* Suppose yourselves on a hill-side, on a summer day, looking 
down on such a plantation of Larches. The whole upper part of it 
will appear as one continuous sheet of green. Next make the circuit 
of the plantation : it may still be green on every side, enclosed as by 
a wall of foilage. Then enter the plantation, and walk through it 
in its length and breadth. It will feel everywhere cold and cheer- 
less. Scarce any traces of vegetation will be visible. Little else 
will anywhere meet the eye save the bare trunks and withered 



LETTER VII. . 67 

17. Add to the agency of the causes already speci- 
fied, that of a thousand other destructive influences, 
which come of the sundry and manifold changes of 
the world ^' — frost, fire, hurricanes, lightning — the 
necessities and caprices of man himself ; and a calcu- 
lation of chances will put it beyond all doubt, that the 
far greater number of all sorts of trees, perennial as 
" the everlasting hills," as I maintain they naturally 
are, must perish at no very remote period from their 
origin ; and that ultimately, though at no definite time, 
even the oldest and the greatest of them must disap- 
pear from ofi* the face of the earth. — I am, &c. 

branches of the trees. The whole plantation will contrast remark- 
ably with the Dunkeld Larches, — the reason of which, as of the 
entire aspect of both, you have in the text. Such a plantation may 
be compared to a vast marquee, the framework and supports con- 
sisting of long wooden poles, the covering of green baze. 



LETTER VIII. 



" Wherever a bud is, it contains within itself the germ of an entire 
plant." T. Appleby. 

" Les bourgeons donnent naissance a des scions ou jeunes branches 
chargees de feuilles, et le plus souvent de fleurs. Chaque bourgeon 
a une existence en quelque sorte independante de celle des autres. 
M. Du Petit- Thouars les regarde comme analogues, dans leur 
developpement et leur structure, aux embryons renfermes dans 
rinterieur des grain es, qui, par Facte de la germination, develop- 
pent une jeune tige que Ton pent comparer, avec juste raison, au 
scion produit par revolution d'un bourgeon. Aussi donne-t-il a ces 
derniers le nom dienibryons fixes ou adherens, par opposition a celui 
dJemhryons libres, conserve pour ceux renfermes dans I'interieur de 
la graine." Richard. 

November 11, 1854. 

My Dear Sons, 

1. I have now completed the expository part of my 
subject. It remains for me to substantiate the allega- 
tions made, and, if possible, to raise to the level of a 
sound theory what as yet can only be regarded as a 
pure hypothesis. To this task I shall address myself 
in this and subsequent letters. 

2. It will I think at once be obvious to you, that all 
I have to do is to make good the allegations I have 
made as to the nature of trees. If this can be done, — 



LETTER VIII. 



69 



if I can prove that what I have affirmed concerning this 
is true, the other allegations as to the natural longevity 
and the natural size of trees, will necessarily be true also- 

3. Now the evidence to be adduced will consist in 
shewing, first, That the annual growths emanating 
from the buds constitute, severally, perfect and inde- 
pendent plants ; and that a succession of such plants 
may be kept up from year to year, and for an indefi- 
nite period, from buds alone ; — and, secondly, That the 
same year they are produced, the plants or growths 
in question (save only the newly -formed buds) die, and 
never live again ; or, in other words, cease to be, and 
never afterwards become the seat of any vital action. 

4. All this it will be incumbent on me to make good. 
Beyond this, however, I do not see that anything will 
remain to be done, unless it be to add strength to my 
argument by adducing the concurring testimony of 
others in favour of it, and to meet objections that may 
be advanced against it. And with regard to that tes- 
timony I may in anticipa^tion observe here, that singu- 
larly strong and varied as it will be found to be, its 
great value will lie in its being thoroughly independent 
and undesigned. 

5. My first endeavour, then, will be to shew that 
the annual growths which issue from the buds consti- 
tute, severally, perfect and independent plants ; and 
likewise, that a succession of such plants may be kept 
up from year to year for ever, from buds alone. 



70 



LETTERS ON TREES. 



6. On each returning Spring, we see the buds on 
the stems of the previous year first sweUing and after- 
wards sending out new stems, which in themselves 
and in their appurtenances are precisely similar to 
those which the seeds send up. Like them, they are 
furnished with leaves and roots, they form buds, and 
they put forth flowers and bear seed. Now, in this 
annual formation we have, as the produce of the buds, 
all the parts that are essential to the constitution of 
perfect plants ; and, while the plants which thus issue 
from the buds produce buds in their turn for the evo- 
lution next year on the same tree of other like plants, 
they produce seeds also for the evolution elsewhere of 
precisely similar plants. 

7. The fact that the buds in question evolve the seed, 
— that, while they give rise to other structures in every 
respect identical with those which come of the seed, they 
are themselves adequate to the production of the seed, 
— this, to my mind, is proof sufficient that the buds are 
physiologically co-ordinate with the seed, and that 
their produce is equally with that of the seed entitled 
to be regarded as distinct plants. In order, however, 
the more fully to demonstrate the accuracy of this 
assumption, — in order the better to satisfy you as to 
the proper individuality of each and all of the growths 
thus formed bv the buds of trees, and their claim 
rightfully to be regarded as perfect plants, — and like- 
wise as to the capacity of each of them to reproduce 



LETTER VIII. 71 

its kind annually in endless perpetuity from buds, I 
will adduce further proof. And, in the first instance, 
I shall refer you to the potato-plant, — a plant which, 
though it never grows up into a tree, contains all the 
elements of a tree, and is equally perennial in its 
duration as any tree. 

8. The tuber familiarly known as the potato bears 
a very close resemblance to the yearling shoot or stem 
of a tree. It is confessedly of the same nature with 
such a shoot. It is, in fact, an underground stem, and 
consists of a layer of bark and a layer of woody tissue 
enclosing a mass of pith, and furnished with buds. 
This underground stem, when planted in Spring, sends 
out from each of its buds a growth, which has a stem 
(underground) and roots and leaves and flowers, and 
which forms buds and seeds — structures that are the 
exact counterparts of those composing the growths 
that proceed from the buds of trees. Does any one 
ever doubt that the annual potato-growths which he 
sees in the fields are perfect and independent plants ? 
Does any one doubt that from the buds alone, without 
ever having recourse to seed, a succession of such 
potato- plants may be kept up from year to year for 
ever ? I apprehend not. 

9. The tree-plant and the potato-plant, each growing 
from buds after its kind, are in fact identical in con- 
stitution and structure. The only difference between 
them lies in the situation of their respective stems, — in 



72 



LETTERS ON TREES. 



the changes which these and their roots respectively 
undergo, — and in the habitudes of their respective off- 
spring. Thus the stem of the tree-plant grows above 
ground, that of the potato-plant under ground ; the 
dead stem and roots of the tree-plant continue unde- 
composed and entire for years and ages, those of the 
potato-plant decay early the following year — its roots 
perishing, in fact, the same year with the leaves ; 
the offspring of the tree-plant grow together, and 
as parasites on the persistent dead remains of their 
parent, which serve as a common axis on and around 
which they grow — those of the potato-plant strike 
down singly and separately into the soil, and have 
no connection with any portion of their parent, the 
remains of which have in fact ere this stage of their 
growth wholly disappeared, — and nothing left around 
which, as a common centre and a mechanical support, 
they could grow as parasites. Had it suited the pur- 
poses, immediate and remote, which the Author of 
^fature had in view in giving them existence, we might 
have had the respective peculiarities of these two kinds 
of plants completely reversed. The potato-plant and 
its progeny might have grown together parasitically, 
and by their aggregation have formed a true potato- 
tree. Fantastic, doubtless, would have been the aspect 
of such a tree ; but it would have possessed, as a whole, 
the same individuality which common opinion ascribes 
to an ordinary tree, and the several plants composing 



LETTER YIII. 



73 



it would have been regarded and spoken of as mere 
annual growths. The tree-^^lant, on the contrary, and 
its progeny, might have grown and extended them- 
selves year by year as distinct and separate plants, 
and the so-called annual growths or shoots been 
looked upon as perfect and independent plants. They 
could not, in this case, have been called tree-plants ; 
yet such might have been the constitution and ha- 
bitudes of the oak-plant, of the beech-plant, and 
others. 

10. But we need not have recourse to a speculation 
of this kind. We cannot, it is true, cause the potato- 
plant to grow after the manner of the tree ; but we 
can cause the individual plants composing the tree to 
grow after the manner of the potato, and may see their 
shoots striking down separately into the soil, and 
growing up independently one of another, the stems 
themselves (the counterpart of the tubers), to which 
were attached the buds from which the shoots sprang, 
speedily rotting and passing away. We can plant the 
willow as we do the potato, and with like results. 
Were it to serve any good end, we should have our 
willow-fields as we have our potato-fields. In precisely 
the same way as year by year we raise a crop of 
potatoes, and with as much ease, we might raise 
annually a crop of willows. Cutting off the last year's 
shoots from a willow-tree, and planting them in a moist 
soil, we may obtain as many young willow-plants and 



74 



LETTERS OIN TREES. 



embryo wiilow-trees as we have planted shoots, all of 
them as independent of the parent tree as they are 
independent one of another, and each one of them as 
truly an individual as is the produce of the potato- 
bud. 

11. The common Strawberry affords a somewhat 
different, but in principle the like illustration as the 
potato. The stem of the Strawberry is above-ground, 
but possesses such length and tenuity as makes it lie 
sessile or recumbent on the soil. The young plants 
that come from its buds, finding themselves thus, in 
contact with the ground, straightway strike down into 
it, and the stem decaying and disappearing, the con- 
nection between them and the stem is thus severed, 
and they grow up as separate and distinct plants. But 
for this accidental tenuity of its texture (so to speak) 
the Strawberry stem might grow erect, the roots of 
the several plants might creep down alongside of it, 
and so a Strawberry-tree, or at least a shrub like the 
rasp or the currant, be produced. Analogous to what 
I have just mentioned as the natural habit of the 
Strawberry, is an occurrence observed a few years 
ago by a friend of mine in a Fir-tree. This tree had 
chanced to be broken across near the butt, and had 
fallen to the ground, — without, however, being com- 
pletely severed from the short stump left standing. A 
small strip of wood and bark still connected them. As 
the tree thus lay, one of its branches being in direct 



LETTER VIII. 



75 



contact with the ground, threw out fibres, which took 
root separately. And at the time it was examined by 
my friend, some years after the accident, this branch, 
which had assumed a tolerably erect attitude, was in 
the course of establishing for itself an independent 
footing, and of growing up into a tree, amid the decay 
and ruin of its prostrate and dead parent. 

12. It is onlv necessary further to advert to the 
processes of grafting, budding, and layering. These 
processes seem to me to furnish unequivocal evidence 
that the allegations made as to the annual growths on 
trees are well-founded, and indeed to be themselves 
explicable only on the principle of my theory. From 
the yearling bud taken from one kind of tree and duly 
grafted on another of the same natural family, though 
of a different species, we get the first year a growth, 
and in the course of years a tree, exactly similar to 
the tree and to the other growths of the tree whence 
it was taken. And the tree thus derived, though 
growing on another, preserves nevertheless its own 
distinctive character, has its own peculiar leaves and 
blossom, produces its own pecuhar fruit, and is in 
every respect as perfect a tree as if it had been raised 
from a seed, and had grown up independently from 
the soil. 

13. Nor is it unimportant to observe, as exemphfied 
in our various fruit-trees, that any particular variety 
may be in this way not only multiphed indefinitely, 



76 



LETTERS ON TREES. 



but preserved in perpetuity^ — although (from accidental 
causes, however, as explained in the preceding letter), 
the original tree will not and cannot continue to last 
for ever. The late Mr Knight, indeed, as is well 
known, maintained the contrary. Participating in the 
popular belief that there is a fixed period of life for 
every tree, and one common period of death for all its 
parts, he held that a young shoot taken from an old 
tree could live only as long as the tree, and would die 
with it, i. e. supposing that it died from natural causes. 
In this way he accounted for the disappearance, or at 
least the scarcity of several once well-known fruit- 
trees, such as the Bed-streak and the Golden-pippen. 
His views, however, have not been confirmed by the 
observations and the experience of others. The fact 
which he thus endeavoured to explam has been shewn 
to be exceptional, and referable when it does obtain to 
an entirely different principle.* 

14. Similar remarks to those now made in regard 
to grafting apply to the analogous processes of pro- 
pagation by slips or layers, and to the indefinite mul- 
tiplication and endless perpetuation of such trees (the 
Willow, for example) as admit of being reproduced in 
that way. It is observed by Professor Henslow, that 
all the Weeping-willows in Europe are said to have 
been derived from cuttings taken from a single tree, 

^ Balfour, Class-Book of Botany, pp. 665-8. See also Letter 
xvii. section 8. 



LETTER VTll. 



77 



and this, probably, still growing in Africa.* Now, 
were Mr Knight's views correct, or were the prevail- 
ing theory as to the nature of trees a sound one, these 
Willows, though themselves to all appearance trees, 
would in reality be nothing more than the developed 
state" of the original and proper tree. There could 
not with propriety be said to exist in Europe a genuine 
Willow-tree of this kind. It might be feared, at least, 
if not confidently anticipated, that over every part of 
Europe they would all die about the same time, and 
simultaneously with the death of their African pro- 
genitor ! f 

15. Such is my argument. It goes to place the bud 
on a level with the seed, and the growth that comes 
from the bud on a footing with the seedUng plant. It 
goes also to invest the annual cylinder of woody tissue, 
formed in connection with the several growths of the 
year, with the character of roots. To my own mind, 
the proofs now advanced in support of the former of 
these positions are clear, unequivocal, and decisive. 
The evidence in favour of the latter, in as far as not 
included, directly or by implication, in the former, or 
not already adduced in Letter V., I reserve for the 
present. There are those, however, who would regard 
them as insufficient. Dr Carpenter, for instance, would 
take exception to the main assumption. He would 

* The Principles of Descriptive and Physiological Botany, 242. 
f Henslow, Ihid, p 242, 



78 



LETTERS ON TREES. 



refuse to co-ordinate the bud with the seed; and would 
maintain that the produce of the bud is none other 
than the result of a process of " continuous growth," 
a mere extension of the parent tree, and that this tree, 
sprung originally from a seed, constitutes but a single 
or an individual plant. The adherents of Mirbel, on 
the other hand, holding that the woody cyhnder is 
altogether a sjyecial structure, and formed in situ, 
would deny to it the character of 7^oots, And taking 
up this position, they might retort upon me these two 
questions — fi^^st, Where are the roots of your alleged 
annual tree-plants ? and, secondly, What is there in 
confessedly annual and true plants analogous to the 
woody cylinder of the tree ? 

17. The objections which may be thus or otherwise 
urged I will not now stop to consider. They will en- 
gage our attention in future letters, in which also, from 
the considerations to be therein adduced in answer to 
those objections, I hope that both the theory itself and 
the evidence in support of it will come out still more 
clearly and decisively. And asking of you meanwhile, 
and till those objections are disposed of, only a provi- 
sional assent to this branch of the theory, I will, in 
my next letter, endeavour to prove that the young 
plants which in spring issue from the buds are strictly 
annuals — that is to say, that they die the same year, 
and never afterwards live. — I am, &c. 



LETTER IX. 



" Nature, indeed, yearly perishes." 

Kev. Archibald Alison. 

" Our very life is nothing else but a succession of dying ; every 
day and hour wears away part of it ; and so far as it is already 
spent, so far we are already dead and buried," 

Jeremy Taylor. 

" All vital affinities are of transient duration only." 

William Pulteney Alison. 

December 23, 1854. 

My Dear Sons, 

1. But for the demurrer entered at the close of my 
last letter, I should now unhesitatingly speak of the 
produce of the buds as real plants, each perfect and 
complete after its kind. I will henceforth call them 
such notwithstanding, — under reservation, however, of 
the objections to my argument hereafter to be con- 
sidered. And I now proceed, as proposed, to make 
good my other allegation respecting the plants, — to 
wit, that they are mere annuals, living only 07ie year, 
losing their vitality the same year that they spring 
up, and never afterwards becoming the seat of any 
vital action, or the subject of any vital change ; and 



80 



LETTERS ON TREES. 



farther, that they are essentially independent, that is, 
physiologically, or in respect of their vital relations, of 
the stock on which they grow. 

2. That at the close of the year the young plants 
die, and never afterwards live, is sufficiently obvious 
as regards the leaves and flowers, which wither, fall 
off, and completely disappear. How large a part these 
form of the whole annual vegetation of a tree, it is 
unnecessary to insist upon. The only question, there- 
fore, is as to what remains of the other parts of the 
plants — viz. the roots and stems. 

3. Now on what grounds are we entitled to affirm 
that these stems and roots then die and never live 
again ? 

4. To pave the way for the evidence to be adduced, 
let us dwell for a little on some considerations con- 
nected with general physiology, comparing and con- 
trasting, as we proceed, animals with vegetables, and 
the everlasting trees producing timber for the use of 
man, with the annual corn-plants which supply him 
with his daily bread. 

5. Consider, then, first of all, what is true of the 
whole organised creation, of vegetables equally with 
animals, of animals in common with vegetables, that 
all vital action is of exceedingly short duration in any 
organised structure. The chemical affinities by which 
the various organic compounds are formed, and the 
plastic affinities by which these compounds are subse- 



LETTER IX. 



81 



quently transformed into the various organised struc- 
tures — and these again knit together and built up into 
the several plants and animals which we see around 
us, — and which affinities are the most general and fun- 
damental of all vital actions, — are exceedingly transient 
in their agency. Their office may be said to cease in 
each structure on the completion of the structure ; and 
if this structure have no special purpose to serve in 
Nature other than that connected with its formation 
as an organised tissue, — if the object of its existence 
end with its formation, its vitality may be said to cease 
with the play of the chemical and plastic affinities by 
which it was formed ; and losing its vitality, it tends . 
(as is the tendency of all dead organic matter) to 
revert back to the condition of inorganic. Add to this, 
that the more active and energetic the agency of these 
affinities, i, e, the more rapid the formation of the 
structure, the shorter is the duration of its vitality. 

6. If, on the other hand, the structure have some 
specific end to serve; and if, in order thereto, its 
maintenance for a time in a living state be required, 
this can be accomplished only by a continual change 
and reneival of substance. For the general law of tran- 
sient vitality still attaches to its several molecules ; and 
these, as they die, must be removed and replaced by 
new — a process involving the continued agency of the 
affinities by which the structure was at the first formed, 
exerted on foreign matters taken in from without — 

F 



82 



LETTEKS ON TREES. 



involving also the agency of oxygen to effect the dis- 
integration and removal of the old. To this process 
physiologists give the name of interstitial or molecular 
nutrition. 

7. If the special end which the structure has to 
serve be merely mechanical^ as is the case, for example, 
with bone and cartilage, the general observation now 
made embraces all that need be said as to its vital 
relations. But if its end be higher than this, as is the 
case with the secreting cells and glands (both vegetable 
and animal), with the muscles also, and with the brain 
and nerves of animals, it will have, superadded, a suit- 
able specific vitality ; and then, there is this further 
law, that every exercise of its proper function is more 
or less exhaustive, as well of the general as of the 
specific vitality of the structure ; and that just in pro- 
portion to the amount and frequency of the exercise. 
Every muscular effort we make, every exercise of 
thought and will, exhausts the vitality of so much 
brain and nerve and muscle — involving thereby the 
diminution or loss of the specific power — entailing also 
the death and removal of so many of their moelcules 
— necessitating likewise their replacement by new 
ones ; and that in the exact measure and proportion 
of the acts of thought and volition and of muscular 
exertion. But observe, further, as the subsequent 
result of that exercise, that, under favourable circum- 
stances, the restorative process outruns, within certain 



LETTER IX. 



83 



limits, the destructive ; and that the structure acquires 
ultimately an increase of bulk and power. 

8. All vital action, then, is exceedingly transient in 
any structure. The greater the rapidity of its forma- 
tion and growth, the more frequent the exercise of its 
own peculiar function (if it have any), and the greater 
the energy of this exercise, the shorter time does the 
structure retain its vitality ; while its continued main- 
tenance as a living structure can be accomplished 
only by an incessant change and renewal of its consti- 
tuent molecules. So true is it that we begin to die as 
soon as we begin to live {nascentes morimur) ; that our 
very life is nothing else but a succession of dying ; 
that every day and hour wears away part of it ; and 
that, so far as it is already spent, so far we are already 
dead and buried — a truth, however, which has only 
been recognised in all its fulness by physiologists 
within these few years, and which was perhaps first 
brought thus prominently into view as a principle in 
physiology by Dr Carpenter. 

9. If these views as to the general nature of vitaUty 
be correct, it will be a fair inference that the absence 
of any such process of interstitial or molecular nutri- 
tion in a tissue or organ, after its full development, 
is equivalent to that tissue or organ being destitute 
of vitality — to its being no longer the seat of any 
vital change or action. It will be a proof that, 
however it may retain its characteristic appear- 



84 



LETTERS ON TREES. 



ance, and its ordinary physical qualities, it is really ! 
dead. 

10. jSTow, how stands the case with Vegetables? It ; 
is on all hands admitted, that such a process has no 
place in their economy. No removal of their sub- 
stance and replacement of this by new tissue ever 
takes place. The tissues composing them undergo no 
change of that kind. Once formed, they are never 
afterwards the seat of any change corresponding to 
the renewal of substance which is continually going on 
in the hving tissues of animals.* 

11. And this is true of all vegetables without excep- 
tion — of the perennial tree equally with the annual 
plant. They stand in this respect on precisely the 
same footing. Are we not warranted then in saying, 
that the absence of all change of that kind in the stems 
and roots that remain after the fall of the leaves, and 

" The economy of vegetables is fitted for their office of con- 
stantly converting inorganic into organised matter, by this peculi- 
arity, that their nutrition is maintained without any such function as 
the interstitial absorption of animals ; and necessarily involves, 
during the whole time that any vital actions are going on, continual 
additions to their substance." — Alison, Outlines of Physiology, 3d 
Ed. p. 12. 

" In vegetables there is none of that absorption of the different 
parts which takes place in animals. The matter of which they are 
composed, being once deposited, is never taken up again ; v/hilst in 
animals there is a constant process going on, by which the old matter 
is taken away and the new deposited, and the organs thus renewed." 
— Dr Ware of Philadelphia, m his Edition of Smellie's Phil of Nat. 
Hist., Introduction, chap. ii. 



LETTER IX. 



85 



flowers, and fruit, goes far to make good our assertion, 
that the parts in question then die, and never Hve 
again ? 

12. If we pursue this matter a little further, we 
shall not only see still more clearly, I think, the reason 
of this difference in the constitution of plants and ani- 
mals, but be able to trace a closer affinity between the 
tree and the annual in relation to the duration of their 
vitality — nay, an actual identity between them in this 
respect. 

13. The objects for which animals exist, and for 
which they have been created, may, in a general way, 
be said to have reference to the mental powers bestowed 
upon them. Those objects require the maintenance 
of the animal structures, in a state of vitality and effi- 
ciency, for a certain time, which is very various in 
different structures and in different kinds of animals. 
Agreeably to the laws of vitaHty, this can be accom- 
plished only by an incessant change and renewal of 
substance ; and accordingly this change forms a dis- 
tinguishing characteristic of the vital actions of animals. 
To this it may be added, that their several structures 
are designed either to serve as the seat or the instru- 
ments of the mental principle within them, or to 
provide for the continued maintenance of the entire 
organism. 

14. On the other hand, the objects for which vege- 
tables exist have reference to animals. Vegetables 



86 



LETTERS ON TREES. 



exist only in subordination to animals ; and the objects 
of their existence are as various as their kinds or 
species. One is, the formation of organic matter for 
the use and sustentation of animals. That, indeed, is 
the first and chief end of their existence, and the only 
one that need engage our attention here. 

15. Observe: All organic matter comes from the in- 
organic world — from its water, its air, and its soil ; 
and sooner or later all organic matter is resolved back 
again into air, earth, and water. Dust thou art, and 
unto dust shalt thou return." That is the beginning 
and the end, the source and destiny of the material 
part of every hving thing. It is true of animals as it 
is of vegetables. They are linked corporeally to the 
dead earth as closely as vegetables are. Equally with 
vegetables, they are beholden to it for their very 
fabric, for the materials out of which this is built up 
and fashioned, and by which it is continually renewed 
and upheld during its allotted time. 

16. But observe further : Animals require for their 
sustentation that this inorganic matter shall first have 
been transformed into organic. They cannot them- 
selves subsist on inorganic matter as such. Neither 
have they the power of effecting that transformation 
for themselves. 

17. Vegetables, however, can do both. Their proper 
food is carbonic acid, water, and a few simple salts ; 
and they can so act upon these, and upon ammonia, as 



LETTER IX. 



87 



to form cellulose, starch, sugar, oil, gluten — nay, albu- 
men and fibrine, and the several structures and juices 
of which they consist. In forming these, they fulfil 
the end of their being ; and having no object to serve 
beyond this or not arising out of this,* and having 
made provision concurrently with it in the form of 
buds, or seeds, or both, for another race of the like 
kind with themselves, they die. And accordingly, 
they neither need nor do they exercise any such func- 
tion as the molecular nutrition of animals. 

18. Let me take you one step farther. Dependent 
as the whole animal creation thus is on the vegetable, 
man is in an especial degree, and in an infinite variety 
of ways, beholden to it. Gifted with reason, which 
has been denied to the brute animals, his merely natu- 
ral wants are far greater than theirs ; while the reason 
which has been given him, and, as arising out of this, 
the objects of his existence and the manifold relations 
in which he is placed — all these multiply his wants 
to a degree which it is scarcely possible for us to 
conceive. 

* "Or not arising out of this." One exceedingly important object 
of their existence is that of maintaining the atmosphere in a state of 
purity for the respiration of animals. This they accomplish by the 
power they possess of decomposing carbonic acid — retaining and 
fixing the carbon within themselves, and setting free the oxygen. 
But the carbonic acid existing in the atmosphere forms one main 
source of their food, and the accomplishment of the object here 
referred to may be said to spring from that mentioned in the text. 



88 



LETTERS ON TREES. 



19. Now, his various wants are mairdy such as vege- 
tables only can meet. We have already seen how 
dependent he is, in common with all animals, on vege- 
tables for food; and we may just add, with reference 
to this, that besides the enormous quantities of corn 
and other kinds of vegetables grown annually, to be 
directly consumed by him, a large part of every year's 
vegetation is raised for the support of animals which 
he lives upon, and rears exclusively for their use as 
food. The grass of the field is thus indirectly but as 
truly his stay and support as the corn. But, passing 
from this class of vegetable productions, and from that 
more immediate and pressing want which they supply, 
let us ask what kind of vegetables come next in impor- 
tance to man — what sort of vegetable produce is he 
most dependent on ? Were we to say trees and tim- 
ber, and trees as producing timber, should we be far 
from the truth ? Doubtless not. Wanting timber, 
what could man have done ? What would have been 
— what would now be his condition ? He could have 
done very little towards subduing the earth, or replen- 
ishing it ; he could have made little or no progress in 
arts, or commerce, or civihsation. It may be ques- 
tioned whether he could have continued on the earth 
at all, so intimately are the properties and uses of 
timber bound up with the very conditions of his exist- 
ence. 

20. We are now arrived at the point to which I 



LETTER IX. 



89 



wished to bring you. We have seen what are the 
more special objects of the existence of vegetables, 
and what the character and duration of their vita- 
lity. We have seen also the importance of timber to 
man, and may infer from this the main object of the 
existence of trees and tree-plants. And we may now, 
I think, see a reason why the stems and roots which 
remain after the fall of the leaves need not, nay, why 
they should not, any longer retain their vitality. For 
the chief object of the existence of trees and tree- 
plants is plainly the production of timber ; and, its 
production going on by the formation year by year of 
distinct layers of woody matter, there is a strong 
presumption, from the considerations now adduced, 
that on the accomplishment of this object each year, 
both the timber produced, as well as the plants pro- 
ducing it, will no longer be either the seat or the 
subject of vitality. We may thus perceive why the 
production of our timber-stuffs " need not differ in 
principle from the production of our " bread-stuffs,'' 
I say in principle, for there is a difference. It is one, 
however, in mode only ; a difference in the accidents, 
not in the essentials of its production, the reason for 
which also we may readily perceive. For, although 
for some purposes the wood of the seedling or sappling 
is useful, yet for most purposes the aggregate collection 
of the wood of several years successive tree-plants is 
necessary. Indeed, it is only such an aggregate that 



90 



LETTERS ON TREES. 



we regard and speak of as timber; and while for many 
purposes immense aggregations of this kind are needed, 
they could have been produced only, consistently with 
a strict adherence to the general analogy of vegetable 
life, by such pecuharities in the modes and habitudes 
of growth of the various tree-plants as it has been my 
object in these Letters to point out as belonging to 
them. 

21. In truth, then, as I believe, just as we have 
annually a crop of corn, so have we annually a crop of 
timber; and just as we stack the one or put it into 
barns of our own building, so does nature stack the 
other for us, laying it up and preserving it in a 
way we cannot, leaving it to ourselves to draw from 
her store, and turn it to our purposes as we need, or 
as we please, after the stack has stood ten, or fifty, or 
a hundred, or a thousand years. A tree is but a 
timber-stack of nature's building. 

22. .But however this may be, the fact is, as we have 
seen, that after its formation the woody matter of a 
tree undergoes no such molecular change of substance 
as we have reason to believe essential to the continu- 
ance of vitality in any organised structure. And to 
this it may be added, that after the year of their 
formation, the several layers of wood and root undergo 
no farther extension by growth. So .unchanged do 
they remain, that from an examination of the woody 
cylinders of an old tree, we may readily gather, nay 



LETTER IX. 



91 



with the utmost precision determine, what were the 
characters of the seasons 500 or 1500 years ago. 

23. But, allowing that no such molecular change 
takes place in the woody matter, nor any farther 
increase of growth, the sap continues year by year to 
move through it ; and this movement is a vital action, 
and due to vital agency : True. And is not this a 
proof that the old wood still continues to be possessed 
of vitality ? In my next letter we shall consider 
whether it be or no. — Meanwhile, believe me, &c. 



LETTER X. 



" Ubi stimulus, ibi fluxus." 

" It is evident that the force, whatever be its nature, by which 
the continued movement is kept up, must be developed by the pro- 
cesses to which that movement is subservient ; in other words, that 
the changes involved in the acts of nutrition and secretion are the 
real source of the motive power." Dr Carpenter. 

" If a piece of bladder be tied over the surface of a vine-stump, 
when the sap is rising rapidly, it soon becomes tightly distended, and 
will ultimately burst." Professor Henslow. 

January 7, 1855. 

My Dear Sons, 

1. I concluded my last letter by observing, that 
although (as we there saw) the old stems and roots 
undergo no organic change of any kind after the year 
they are formed, — neither an increase in length or 
thickness, nor a renewal of substance, — the sap, never- 
theless, moves through them during the next and 
several subsequent years. And I remarked, that this 
might be regarded as a proof that they retain their 
vitality for a much longer period than I allow they do. 

2. It does not therefore follow, however, that the 
parts in question are alive. To warrant such an infer- 



LETTER X. 



93 



ence, it must be shewn that they contribute actually 
and actively toAvards the movement ; and that, too. in 
a way not referable to their porosity merely, or to any 
other simply physical property they may possess. 
There is a familiar experiment which you have your- 
selves often made for your amusement — that of strew- 
ing cress or mustard seeds on a bottle or other vessel 
covered with flannel and placed in a shallow dish, which 
you fill up, and from time to time replenish with water ; 
the result being, as you know, that in due time the 
seeds germinate and cover the vessel with living 
plants. Here, in this simple experiment, the flannel 
by reason of its porosity conveys, or rather allows the 
passage of the water from the dish to the living seeds 
and plants. No one, however, would for a moment 
imagine that the flannel is alive. jSTo more are we 
entitled to infer that the old stems and roots of a tree 
are alive because of the sap moving through them to 
the living and growing parts above. They may be 
merely the medium or channel of its transmission,, and 
may contribute towards this in the same way that the 
flannel does, and in no other. Their vitahty, there- 
fore, if they be really possessed of any, must be estab- 
lished on other grounds than this. 

3. Unquestionably, the circulation of the sap is a vital 
action, and due to vital agency. This agency, how- 
ever, has its seat or centre in the hving buds, and in 
the living structures proceeding from them, and actually 



94 



LETTERS ON TREES. 



growing. It is directly connected with the vital pro- 
cesses going on there during the spring and summer 
— nay, it is exclusively dependent on these processes. 
The first or earliest movement of the sap in spring is 
in the immediate vicinity of the buds. The fluid 
there, previously at rest, is the first to be set in motion, 
and its movement is determined by the act of vegeta- 
tion beginning in the buds under the quickening 
influence of the sun. The subsequent and very rapid 
increase in the activity of that process necessitating 
additional and proportionably larger supplies of sap, 
an agency is exerted which operates downwards in 
the direction of the soil, and causes the nourishing 
fluid to ascend. And it is further of consequence 
to remark, that the whole season through, the amount 
of sap drawn from the soil, and the rapidity of its 
ascent through the trunk to the parts above where 
vital actions are undoubtedly going on, are entirely 
regulated by the activity of these actions. The sup- 
plies furnished, and the times and rates of their delivery 
to the living and growing parts above, are in the exact 
measure and proportion of the demands they make. 
They are large or small, slow or rapid, just as the vege- 
tation is scant or luxuriant, languid or energetic. 

4. Of all this we have several decisive proofs. If 
any single branch of a tree, standing in the open air, 
be carried through and led into a hot-house hard by, 
at a time when no vegetation is going on in any part of 



LETTER X. 



95 



the tree, and the sap is everywhere quiescent, the buds 
of that branch will vegetate, and the sap circulate 
through it, while as yet nothing of the sort is in pro- 
gress in any of the other branches of the tree.* It 
cannot surely be that the roots and stems should exert 
an agency so exclusive, or have any share in the pro- 
duction of a change so strictly local. Conversely, if 
the buds be cut oii from a branch prior to the com- 
mencement of the annual process of vegetation, no sap 
will pass into that branch during the entire spring and 
summer, although the other branches not thus muti- 
lated will be full of it. Again, if at a later period in 
the season the leaves be stripped from off a branch, 
the flow of sap through it will speedily if not at once 
be effectually and permanently arrested. 

5. What may be the nature of the agency thus 
exerted in the living buds and leaves, or of the force 
emanating from them, which thus causes the sap to 
circulate, and which regulates the quantity of it pass- 
ing through the old stems and roots, — and what the 
mode or manner of its action, it is not easy to say. 
It is clearly a force acting a f route, or in advance, and 
attracting the sap, — in contradistinction to a force 
acting a tergo, or from behind, and propelling the 

* " The excitement of vital action in a branch of a tree exclusively 
exposed to the sun, is the cause, not the effect, of an exclusively 
increased flow of the sap into it." — Alison, Outlines of Physiology y 
3d ed. p. 70. 



96 



LETTERS ON TREES. 



fluid.* But be its nature what it may, the old roots 
and stems may be no farther concerned in it, than as 
being the channels through which the nourishing fluid 
passes upwards from the soil. No facts yet known to 
physiologists demonstrate that they are any otherwise 
concerned in it, while those just adduced sufficiently 
account for it independently of them. 

6. But in the course of the season, there is a descend- 
ing as well as an upward or ascending movement of the 
sap. And this other must equally be regarded as a 
vital movement, and equally due to vital agency. 
May not that movement, at least, argue vitality and 
vital ppvfer in the old stems and roots? I apprehend 
not ; and for this reason, — that while the ascending 
current is plainly referable to the processes going on 
in the buds and leaves, to the evolution of which as 
well as its own elaboration it is subservient, the 
descending current now in question is connected with 
the formation of the woody layer all over the exterior 
of the tree, and as plainly referable to the processes 
by which that structure is evolved. This layer is dis- 
tinct from the layers of previous years ; it is a new 
formation, of tlie same year's growth with the young 

^ To Dr Alison, unquestionably, the merit is due of being the first, 
in this country at least, clearly to establish both the reality and the 
importance of this general principle in physiology ; and likewise to 
shew how large a part it plays in the morbid as well as in the healthy 
processes of the living body — in the acts of nutrition and secretion, 
as well as in the movements of fluids. 



LETTER X. 



97 



plants above, and growing concurrently with them. 
And it requires for its evolution equally as these do 
for theirs, a supply of prepared or elaborated sap. 
But the sap is elaborated only in the leaves ; and as 
the woody layer extends from the base of these down- 
wards to the tips of and even beyond the roots of the 
previous year, so the sap can be supplied only from 
above, and must descend in order to reach every part 
of the layer in question, — its descent, however, in 
common with its ascent, being immediately due to 
the attractive force exerted by living and growing 
tissue. 

7. But the agency now dwelt upon as seated in 
the growing parts, and thence exerting an attractive 
influence over the sap, is not the only one con- 
cerned in the movement of this fluid. The well known 
experiments of Hales, and those subsequently insti- 
tuted by Dr Daubeny and others, leave no room to 
doubt, that at the extreme points of the roots (desig- 
nated the spongioles of the roots) there resides another 
and a very efiicient moving power.* Let us consider 

* " Hales cut off the stem of a vine in the spring, when the sap 
rises with the greatest velocity, and luted a tube to the top of the 
stump, bent in the manner we have described in the construction of 
the Endosmometer. As the sap rose into the tube, mercm*y was 
introduced at the open end ; and a measure of the force of the rising- 
sap was thus obtained, and found to equal the pressure of an atmos- 
phere and a half." — Henslow, Descriptive and Physiological Botany ^ 
p. 181. 

G 



98 



LETTERS ON TREES. 



it for a little, and see where it exactly lies, and how it 
acts. The old rootlets and their spongioles have, I 
apprehend, no real concern in it, but only the new — 
those that have grown during the year, which stand 
related to the new plants, and to the corresponding 
layer of woody tissue, and which, as we shall yet see, 
actually begin to grow contemporaneously with these.^ 
It may be supposed, however, to be of the nature of 
an a tergo force — that is, of a moving power acting 
from behind and in the way of propulsion — differing, 
therefore, in its mode of action, if not in its essential 
nature, from that already considered. It is clearly, 
as the facts connected with it show, elective in the first 
instance — allowing certain fluid matters existing in the 
soil to gain entrance within the tree, and rejecting 
others.^ But in the next place, with regard to the 
fluid thus admitted, it is as clearly attractive as is the 
agency of the buds and of the living structures which 
spring from them. So soon, indeed, as it is drawn 

* See Letter XII., Sections 7-13. 

f " If a grain of wheat and a pea be grown in the same soil, the 
former will obtain for itself all the silex, or flinty matter, which the 
water can dissolve ; and it is the deposition of this in the stem which 
gives to all the grasses so much firmness. On the other hand, the 
pea v^ill reject this, and will take up whatever calcareous substances 
(or those formed of lime and its compounds) the water of the soil 
contains, these being rejected by the wheat." — Dr Carpenter. This 
selecting power, however, is limited, as in the case of the animal 
body — substances being readily absorbed which prove hurtful to the 
system, or even fatal. 



LETTER X. 



99 



within the tree by the young spongioles, the fluid 
has no help but to move on and pass upwards. Even 
were there no force in advance, as we have seen there 
is, sucking it upwards, the fluid must needs pass in 
this direction, because driven on by the portions 
subsequently absorbed. Physiologically considered, 
then, the force acting at the spongioles is, I am 
inclined to think, attractive only^ and only indi- 
rectly and mechanically propulsive.* It is one, too, 
I apprehend further, which is strictly subordinate to 
that seated in the living and growing parts above, f — 
the two acting in harmony together, in ways provided 
for by the Creator, but which we can as little fathom 
as we can the essential nature of the powers them- 
selves. In anywise, the facts known to us regarding 

* Professor Henslow, indeed, regards it as a vis a tergo and pro- 
pulsive in its mode of action, — while Dutrochet, regarding it as 
simply phj^sical, resolves it into a principle, of a twofold natm*e, 
designated by him the principle of Endosmose and Exosmose, I agree 
with Professor Henslow that there is a difficulty in resolving the one 
into the other, and feel inclined to reject Dutrochet 's theory 
altogether as inadequate to the explanation of the phenomena 
included under it, — but I differ from Professor Henslow in the view- 
taken of it by him. To my mind, a vis a tergo must lie without and 
beyond the roots, L e., in the soil itself, or the matters contained 
in it. 

Energetic as his experiment vdth the vine shewed this power 
to be, Dr Hales found that, cut off from the force acting above, " it 
soon diminished, and after a time ceased altogether." — Dr Carpen- 
ter, Principles of Physiology} Gen. and Comp,, p. 655. 



100 



LETTERS ON TREES. 



the agency of the spongioles, furnish no grounds for 
ascribing vitahty to the old roots.* 

8. Hitherto, then, we have seen nothing in the old 
stems and roots to lead us to believe that they are 
possessed of vitality. And I would fain persuade 
myself that in the facts which have passed under our 
view, in this and the preceding letter, we have seen 
enough to satisfy us that they are really dead. And 
to the considerations already adduced in behalf of this 
conclusion, I would just add this other. We know 
that after a time, — altogether indefinite, often not 
for many centuries, sometimes within a few years, — the 
earliest formed wood, the heart-wood, as it is called, 
decays and disappears; and that this change may 
proceed to such an extent as to destroy a large part 
of the entire trunk, without in the least degree im- 
pairing the vegetation going on at the extremities, 
and on the exterior of the tree. This it is easy to 
understand on the view we have all along taken 
of the nature of trees, but very difficult on the sup- 
position that a tree constitutes but a single or an 

^ " The spongiole is sometimes spoken of as a distinct organ ; 
but it is nothing more than the growing point of the root, which, 
with a few exceptions, lengthens only by additions to its extremity. 
The soft, lax texture of the nev)ly -formed part causes it to possess, 
in an eminent degree, the power of absorption: but as the fibre con- 
tinues to grow, and additional tissue is formed at its extremity, that 
which was formerly the spongiole becomes consolidated into the 
general structure of the root, and loses almost entirely its peculiar 
properties.''^ — Dr Carpenter, ibid, p. 652. 



LETTER X. 



101 



individual plant, and is endowed with Yitality in its 
every part. On this supposition, such a change 
occurring in the heart-wood should spread, or might 
reasonably be expected to extend to the adjoining 
living parts, and, sooner or later, but before very 
long, to kill the whole tree. This, however, does not 
happen ; nor is the complete and premature decay 
of an entire tree ever due to the agency of such a 
cause. 

9. It has thus, I hope, in this and the two preceding 
Letters, been satisfactorily made out — first, That the 
growths emanating from the huds of trees constitute 
severally perfect and independent plants ; and, secondly, 
That what remains of them, after the fall of the leaves, 
and flowers, and fruit, with the single exception of the 
buds, ceases to live, and never afterwards becomes the 
seat of any vital action. 

10. And if this be conceded, it will probably be 
allowed also, that the view here presented of the 
nature and of the natural longevity and size of trees 
is well-founded ; — that is to say, that a tree is simply 
a corporation sole " — a collection, aggregate, or 
congregation of annual plants of the same species, the 
production of a series of successive years, the indi- 
vidual plants of each year shooting up in spring from 
buds adherent to the persistent dead remains of the 
plants of the previous year, growing as parasites on 
these remains, putting on the character of old age in 



102 



LETTERS ON TREES. 



autumn, and speedily thereafter dying — provision, 
however, having been made by them in summer, in 
and by the formation of buds, for the reproduction of 
similar plants the following year : And that being 
thus evolved, and thus growing from year to year, 
and having no actual limits to their reproduction in 
this way, there is in point of fact no actual limit to 
the age or to the size to which the tree collectively 
resulting from them, or produced by them, may 
attain. — I am, &c. 



LETTER XL 



" Take an octagon building ; paint each side of a different colour. 
Fix eight men fronting severally each side. Call them away, and 
ask them the colour of the building ; and each will give a different 
account. Now, where does the falsehood lie ? Do the same exter- 
nal colours produce different impressions on different eyes ? Is the 
evidence of the senses uncertain ? Are there no fixed principles 
of sensation ? No : the mistake lies in a false inference. Each man, 
instead of confining his statement simply to the part which he saw, 
declares that the whole building, which he did not see, is of the 
same colour with the part that faced him. His senses are correct; 
his belief would be correct, if he would not fancy more than he 
really perceived. Shift the parties, and try if, when placed before 
the same side, they all agree in seeing black, or blue, or red, or yel- 
low, where the colour really exists." — Sewell. 

January 25, 1855. 

My Dear Sons, 

1. Professor Sewell, in his " Christian MoraU^'' 
says truly that " all our knowledge is in fact a 
perception of relations." And, after remarking that 
our ideas of the relations that subsist among the many 
and very various objects of our knowledge, necessarily 
and intuitively spring up in the mind on the very per- 
ception of the relations, he observes that when those 



104 



LETTERS ON TREES. 



ideas seem to vary, **the variation arises, not from a 
different idea following the perception of the same 
relations, but from the perception of seemingly the 
same thing in different relations." Among other illus- 
trations of this observation, he gives that placed at the 
head of this letter, — alleging also that what holds true 
of the perceptions that come to us through the senses^ 
is true also of the perceptions derived through the 
reason, 

2. Comparing, then, our subject — the Tree — to this 
octagonal building, and the details regarding it which 
have engaged our attention, to the several sides of this 
building, let us consider, before we finally take leave 
of it, whether we have examined it in all its relations, 
— whether we have indeed gone completely round it, 
and looked at its every side. 

3. And that we may be well assured that we have 
done so, let us inquire what account other observers 
have given of it. We may not find, perhaps, that any 
one has examined it exactly as we have done, — or 
rather with the view of discovering whether these par- 
ticular relations obtain among its several parts which 
we have seen or fancied to hold. But I have no doubt 
we shall find that every face and side of the building 
has been seen by some one or more observers ; and our 
business will be to see whether or how far the descrip- 
tions given of it by others agree with or differ from 
ours. If they agree, well and good. The coincidence 



LETTER XI. 



105 



will onve us all the more confidence in the accuracy of 
our own survey. If they differ, it will be necessary 
to consider wherein the discrepancy lies. The result 
may be a virtual agreement, — or, perchance, a demon- 
stration that all the while I have been fancying 
in my favourites — the Trees — much more than I 
really saw, — seeing in them relations that existed 
only in my own imagination. Be it so. I hope that 
love of truth is stronger with me than fondness for a 
long-cherished theory, and that once convinced that 
this theory is not what I have hitherto deemed it — an 
expression of the truth — I shall no longer have any 
regard or consideration for it. When one has dis- 
covered that a coin which he valued is counterfeit, 
the best use he can make of it is, to bury it out of 
sight. 

4. To proceed : At the head of every one of this 
series of Letters, I have placed one or more short 
extracts from the writings of various authors, as more 
or less illustrative of the views unfolded in the letters, 
and to serve as a sort of text. I shall now request 
you to give your best attention to such of these 
extracts as bear on our present subject, and also to 
some others which, from their great length, I could 
not make that use of, but which I will now embody 
here, along with such observations of my own in the 
way of criticism or application as may seem naturally 
to arise out of them. 



106 



LETTERS ON TREES. 



5. Turn then to Letter VIII., and read again what I 
have there quoted from M. Richard as to the views 
of M. Du Petit-Thouars regarding the nature and 
capacities of the hud, literally rendered into Enghsh, 
the passage is as follows ; — 

The buds give origin to shoots or young branches furnished 
with leaves and most commonly with flowers. Each bud has 
in a manner an existence independent of that of the others. 
M. Du Petit-Thouars considers them as analogous in their 
development and then* structure to the embryos enclosed in 
the interior of the seed, which, by the act of germination, 
develope a young twig, which may justly be compared to the 
shoot produced by the evolution of a bud. Accordingly, to 
these last he gives the name of fixed or adherent embryos^ in 
opposition to that offree embryos — reserved for those embedded 
within the seed " * 

M. Du Petit-Thouars, you will perceive, maintains^ 
in the first place, that of the several buds on a tree, 
each one is virtually independent of every other bud — 
each having an independent existence of its own ; in 
the second place, that in its development and structure, 
the bud is analogous to the embryo contained in the 
seed ; and, in the third place, that the young plant 
which issues from the embryo within the seed is ana- 
logous to the young shoot which proceeds from the 
bud. The analogy, in respect both of the seeds and 
buds themselves, and of their respective produce, is, in 
his view, as perfect as it is possible to be — amounting 

^ Richard, Op. Cit. p. 103. 



LETTER XI. 



107 



as it does to an identity in nature and character, — in 
structure and function. For he puts the bud on a 
level with the seed, calling them both embryos,'' — 
and he indicates the differences that obtain between 
them by calhng the one a fixed embryo, the other a 
free embryo ; — differences, these, which attach, not to 
the essence of the two objects, but to the ends to be 
accomplished by them in the economy of nature, — 
and which, therefore, important as they are in that 
respect, may, in a physiological point of view, truly 
be regarded as incidental, 

6. It is unnecessary to dwell longer on these views 
of M. Du Petit-Thouars. But familiar as I have been 
these many years with the whole passage in Richard 
which we have just been considering, there is an 
expression in it which has only now for the first time 
occurred to me as peculiar. The seed is spoken of as 
containing an embryo ; and the bud is said to be 
analogous — not to the entire seed, but only to the 
embryo within it. There is a real propriety in this 
distinction. Besides the embryo, there is enclosed 
within the seed a quantity of starch for the earliest 
growth of the embryo. The bud contains none. But 
observe, the pith in the shoot to which the bud is 
attached consists of starch, and holds precisely the 
same relation to the bud, as an embryo, that the 
starch of the seed does to its proper embryo. The 
analogy, instead of being weakened by this distinction, 



108 



LETTERS ON TREES, 



comes out all the stronger. It is the whole shoot, 
with its " adherent " bud. that is the counterpart of 
the entire seed. It is the whole tuber, and not the 
eyes " only, that is the co-relative of the plum of the 
potato-plant. - 

7. Consider next what Mr Appleby — speaking of 
" The Hollyliock and its propagation by cuttings " * — 
says of the bud (Letter VIII.) — 

''Each joint had a dormant bud, which, when isolated and 
placed in shallow pots, in a gentle stimulative, started into 
growth, and soon shewed a shoot projecting above the soil : 
This in time, as the leaves unfolded, pushed forth roots and 
formed a plant. This shews that wherever a bud is, it contains 
within itself the germ of an entire plants which, when correctly 
managed, can be formed into a plant equal in vigour^ and in 
every way as perfect an individual^ as the plant from which it 
was cut or taken." 

In writing thus, nothing seems farther from Mr 
Appleby's mind than any theory or argument as to 
the nature of the bud. And yet his language respect- 
ing it is strikingly in accordance with that of M. Du 
Petit-Thouars, and with the views which have been 
laid before you in these Letters. 

8. I now request your attention to what Dr Ware 
says on the subject (Letter IV.) : — 

" The principal seat of the growth and nutrition of plants is 
in the bark and alburnum, and all the new matter yearly added 
is deposited on the outside of the latter and the inside of the 

* The Cottage Gardener, vol. viii. p. 339. 



LETTER XI. 



109 



former. The growth of one year is only subservient to the cir- 
culation of the next, and is ever afterwards of use merely in 
giving strength and stability to the trunk, in order to support 
the increasing size and weight of the branches and leaves. The 
wisdom and beauty of this provision, by which that portion of 
the plant which has become useless for every other purpose^ is 
thus made to answer a very important end, are suflSciently 
obvious ; and it is rendered necessary by the circumstance 
that plants do not like animals arrive at a definite size and 
there cease, but go on growing to an indefinite extent, and con- 
sequently require corresponding increase and strength in those 
parts which are to support them." 

And again : — 

Those parts of plants which perform the functions neces- 
sary to their nutrition and growth, are strictly annual. So that 
all plants are either annual, that is, wholly renewed every 
year, — or .at least have the circulating vessels and all the 
organs taking an active part in their economy annually re- 
newed." * 

9. In these two extracts, there are several state- 
ments which tally very exactly with mine. Observe, 
first of all, what Dr Ware says as to the indefinite 
growth of trees : — " They do not, like animals, arrive 
at a definite size and there cease, but go on growing 
to an indefinite extent," — an observation, I need 
scarcely remark, which is precisely in accordance with 
what I maintain. Again, Dr Ware virtually says, in 
perfect keeping with my argument, that, in respect 

* John Ware, M.D.— Introduction to his Edition of SmeUie's 
Philosophy of Natural History. 



110 



LETTERS ON TREES. 



of the processes of nutrition and growth," which/ in 
truth, is in respect of iheivliole of their vital actions, trees 
are made up of annuals, — growing upon the remains 
of annuals. And the uses of these remains, in relation 
to the living annuals, he mentions in terms almost 
identical with my own : — " The growth of one year 
(or rather what remains of that growth), is only suh- 
servient to the circulation of the next," — not being 
itself (beyond the year of its formation) the seat or 
subject of any further growth, or indeed of any vital 
action, but simply serving as the channel by which 
the sap passes upwards to the living and growing 
parts above it, and it is ever afterwards of use merely 
in giving strength and stability to the trunk in order 
to support the increasing size and weight of the 
branches and leaves," — that is, it serves as a frame- 
work or scaffolding to the living annuals growing as 
parasites upon it (Letter IV. 7). And important as 
this purely mechanical use which it serves is, it has 
become useless for every other purpose." Though 
clothed and decked in a living mantle of green, it 
is itself really dead. And this beautiful arrangement 
is an express adaptation to the whole nature and 
economy of trees. They go on growing to an inde- 
finite extent," because in the annual formation of 
" fixed embryos" provision is made for such indefinite 
growth : Yet this requires a " corresponding increase 
and strength in those parts which are to support 



LETTER XI. 



Ill 



them." The remains of the seedhng oak-plant would 
be inadequate to support the whole growth of the 
oak-tree's twenty-first year. But it is quite equal to 
that of the second year, as the remains of the twentieth 
are to the twenty-first, — the growth of each year being 
exactly proportioned to that of the years immediately 
preceding and following it, — to the support it has to 
rest upon, and to the burden which in its turn it has 
to bear. 

10. I will now introduce you to M. Mirbel, a bota- 
nist deservedly of great celebrity, with whose views 
on the subject before us I only became acquainted 
(and that by the merest chance) several years after 
my own had been made public. They are contained, 
in as far as known to me, in a paper in the fourth 
volume of the Quarterly Journal of Science, entitled 
" Of the Death of Plants : From the French of M. C. 
F. Brisseau Mirbel." In reading what I shall here 
quote from that paper, you will not fail, I think, to be 
struck with the very close resemblance which his views 
generally and many of his expressions bear to mine. 
JN'or can I forbear expressing my surprise that views 
so detailed, and so clearly and forcibly set forth by 
M. Mirbel, should not have found their way into our 
systematic works on vegetable physiology. 

11. M. Mirbel begins by observing, that 

" Plants, like animals, unless destroyed by disease or casual- 
ties, are doomed to die of old age.^'' 



112 



LETTERS ON TREES. 



He starts, you will observe, from the same point, 
making the same assumption that I do (Letter I. 6). 
And after stating how this law applies to several sorts 
of plants, he goes on to say of trees — 

''In the dicotyledonous class there are enormous trees, 
whose existence seems to date from before the records of his- 
tory^ and which, in spite of their antiquity^ are loaded^ in each 
returning year, with blossom and seed, 

''If we were to view the perennial and woody plants as 
simple individuals, as such we should be naturally induced to 
conclude, that unless destroyed by disease or casualties, they 
were free from the liability to death from old age ; but a due 
consideration leads us to distinguish ia every perennial and 
woody plant, the new part which actually lives and grows^ from 
the old^ which has ceased to grow^ and is dead. 

" I will state this in a broader way. Plants of this nature 
have two modes of propagating their races : one, by seeds — the 
other, by a continuous evolution of like parts. In the first case, 
the seed presents us with an embryo plant, a new and different 
individual, independent, and unconnected with that from which 
it derived its existence ; in the second, we are presented with 
a series of individuals., which issue from the surface the one of 
the other in an uninterrupted sequence, and in some instances 
continue permanently united. But whether individuals of this 
description are produced by seed or b}^ continuous evolution, 
it is certain that they escape, in neither case, the influence of 
time ; while, on the other hand, the succession of individuals, 
or what we may call the race, produced in either of the ways, 
is as clearly beyond the reach of age^ and will endure until 
destroyed by some extraneous cause. 

" We will endeavour to show how these general laws apply : 
— All the parts of the young herbaceous annual are susceptible 
of enlargement ; the ceUs of the tubes, at first very small, are. 



LETTER XI. 



113 



soon after extended in every way; in process of time their 
membranous walls, fortified by the absorption of nutrient juices, 
grow thicker, and lose by degrees their original pliancy. The 
membranes once hardened, excitement ceases to be produced, 
and the vital functions are at an end ; nourishment is no longer 
drawn, growth is at a stand, and the plant, unable to resist 
the ceaseless attacks of the external agents employed by nature 
for its destruction, decays in a short time." ''By renewals of 
the same nature, the life of shrubs and trees proceeds. In 
them, the liber or inner bark represents the herbaceous plant, 
and has, like that^ only a short period of vegetative existence. For 
when vegetation revives in the woody plant on the return of 
spring, it is. because a new liber, endowed with all the properties 
of a young herbaceous plant (annual), has replaced, under the 
cortex or rind, the liber of the preceding year, which has har- 
dened and become wood." 

12. M. Mirbel next refers to certain trees notable 

for their great antiquity, ^ and then proceeds as 
follows : — 

'' All of them, giants as they are, vegetate, as does the 

* " The yews of Surrey, which are supposed to have stood from 
the time of Julius Ccesar, and are now two yards in diameter ; the 
cedars on Mount Lebanon, nine yards in girth, from the measure- 
ment of the learned Labillardiere; the fig-tree of Malabar, according 
to Rumphius, usually from sixteen to seventeen yards round; the 
stupendous chesnuts on Mount ^tna, one of which, Howell tells 
us, measured seventeen yards in circumference; the ceibas of the 
eastern coast of Africa, of such bulk and height that a single stick 
is capable of being transformed into a pirogua, or sailing vessel, 
of eighteen or twenty yards from stem to stern, and of three or four 
in the waist; the boabab of Senegal of ten or twelve yards in girth, 
and, according to the computation of Adanson, 5000 or 6000 years 
old."— (Mirbel, Loc. Cit.) 

H 



114 



LETTERS ON TREES. 



smallest husli^ solely by their herbaceous layer of the liber, 
annually produced at the inner surface of their bark. The 
concentric layers of preceding libers constitute the mass of the 
wood, a lifeless skeleton^ serving solely to support the new- 
formed parts, and to conduct to them the juices by which they 
are fed ; nor is it even necessary for these functions that this 
should be in an entire state. Willows and chesnuts, when 
quite hollow at the heart, still continue to grow with vigour ; 
but in their soundest state strip them of their bark, and they 
quickly perish. 

Thus reflection teaches us that the long life of the greater 
part of trees, and the immortality which at first sight appears 
to have been imparted to others, .... form in reality no 
exception to the general law which destines every organised 
individual to perish in determined course ; since we see .... 
that the concentric layers which constitute the wood or heart 
of the trunks of trees, are no other than the accumulated re- 
mains of hy-gone generations^ in which vegetation and life are 
entirely extinct. 

" This appears to us the true view of the natm-e of the life 
and death of such beings as are constantly regenerated by the 
successive evolution of continuous parts. 

And we may observe, that the liber which is formed on 
the stem of a tree centuries old, if the treee have met with no 
accidental injury to afi'ect its health, enjoys the vegetative 
power in as full force as the liber which is formed on that of 
the sapling ; and that a sound, well-grown scion from the aged 
but healthy tree, affords as good a cutting for propagation as 
that taken from the young one, so that the race might be 
perpetuated by cuttings alone^ without the assistance of seeds. 
From this we are entitled to conclude, that according to the 
course of nature, the progress of regeneration by continuous 
evolution would never be arrested.^ if the over-grown size of 
the branches and stem, the hardening of the wood, and the 



LETTER XI. 



115 



obstruction of the channels which permeate it, did not impede 
the circulation of the sap^ and consequently its access to the 
liber. 

" In fine, what we call death by old age in a tree, to speak 
correctly, is the extinction of that portion of a race which has 
been carried on by continuous evolution ; the inevitable result 
of an incidental death in the liber, occasioned by the privation 
of nourishment. 

In proportion as a tree increases in size, the vessels of its 
ligneous layers become obstructed, and the sap circulates with 
less freedom. Hence absorption and secretion . decrease after 
youth, in proportion as the bulk of the tree is enlarged. The 
liber is less vigorous ; the buds and roots become fewer and 
feebler ; the branches wither ; the stem decays at the head ; 
water settles in the injured parts ; the wood moulders away. 
Ere long, the new liber, the annual herbaceous part of woody 
vegetables, loses the power of completing its regeneration, 
new parts are no longer evolved, and the tree perishes." 

13. But thougli the tree finally perishes, it is not 
from old age. It is from purely accidental causes. 
M. Mirbel has already told us that the tree is in its 
own nature as imperishable as a race^ or as that por- 
tion of a race which constitutes do family, or a house, a 
lineage or a clan. But it is needless to dwell on the 
details comprised in M. Mirbel's paper. I have under- 
lined those expressions in it which bear more directly 
on the views unfolded in these letters. Further com- 
ment than this seems to me superfluous. You can 
yourselves make the application of them to my views. 

I shall only observe that, while, in M. Mirbel's mind, 



IIG 



LETTERS ON TREES. 



the liber ^ occupies tlie chief place, as representing the 
annual in the yearly sucs^ession of individuals, the 
buds are the parts w iich in that respect have the 
chief regard in mine — following herein as I do the 
teaching of M. Du Tetit-Thouars. In every other 
respect, M. Mirbel's /iews and mine completely coin- 
cide. Nay, in as fai as we differ, or rather as he and 
M. Du Petit-Thou? s differ, it will not, 1 think, be 
difficult to shew, as I shall endeavour to Jo m my 
next letter, that there is an intermediate view, which 
will include and harmonise the views of both these emi- 
nent physiologists, and more truly than either of them 
express mine. 

14. There is yet another author whose views I 
wish to place before you — I mean M. Gaudichaud.f 
I extract the account given of them by Professor 
Balfour of Edinburgh, in his Class-Book of Botany 
(pp. 442-444; :— 

A Monocotyledon (Endogen), in its simplest fovn (Fig. 11), 
may be said to consist of an axis producing a leaf (c d)^ and 
a bud (e) at its upper part, and a root (a) below, it may 
be represented as a phyton, or single plant or bad. havixig an 
axis or axial merithal, with a leaf or foliar merithai ( .i), 
divided into a laminar (d) and petiolary portion (r). the latter 
usually sheathing the axis, and a radicular merithal (a), 

* M. Mirbel subsequently saw reason to substitute the Cambium 
for the liber. 

t Reciierches sur I'Organographie la Physiologie at I'Organo- 
genie do3 Vegetaux, 1841. 



LETTER XI. 



117 




whence roots are produced. This phyton is capable of pro- 
ducing others having a similar constitu- 
tion ; and thus a more complicated Mo- 
nocotyledonous plant consists of a series 
of phytons placed one above another, the 
parts being alternate (as seen in the 
adjoining figure, Fig. 12). Each phyton 
has a distinct leaf, producing a bud in its 
axil, or at the part where it is united to 
the axis : it has also an ascending or 
foliar, and a descending or radicular 
system. In the case of the first phyton, the latter descends at 
once into the soil ; but in the case of 
the others, it passes downwards through 
the first axis^ before it reaches the 
ground, or in some instances it appears 
externally at the base of the phyton, 
and thus becomes for a time aerial (r, /). 
A Monocotyledonous plant may thus be 
said to consist of a series of phytons, 
arranged one within [and above] the 
other, with shortened axes. 

A Dicotyledon (or Exogen), on the 
other hand, in its simplest state, may be said to consist of an 




Fig. 13. 



axis producing two leaves at its 
summit and roots below (Fig. 13). 
It may be represented as two 

hytons united, the foliar meri- 

iials (c d) being placed opposite 

0 each other. In the Monocoty- 

edon, each node produces one leaf 
and is unifoliai' ; in the Dicotyledon, two, and is bifoliar. 
This tendency to produce two leaves at a node does not, 
however, remain permanently in all Dicotyledons ; for, 




118 



LETTERS ON TREES. 



by the extension of internodes, the foliar merithals frequently 



Fig. 14. 




become alternate. A Dicoty- 
ledonous plant may be consi- 
5^-c:^i>> dered as consisting of a series 
'^'d Qiphytons (Fig. 14), which pro- 
duce an ascending foliar sys- 
tem, and a descending radicu- 
lar one," — [the series being 
arranged one above and outside 
the other.] 

In the phytons or foliar 
types of these two great classes 
of plants, cells and vessels of different kinds are united ; and 
the phytons may be considered, in reference to the entire 
plant, precisely in the same way as the simple cell is regarded 
when compared with the various tissues forming the compound 
individual. A phyton may be thus regarded as an organ 
furnishing a type of all the parts which enter into the com- 
position of the nutritive and reproductive compound organs. 
While the embryo of phanerogamous (or flowering) plants may 
be considered as a phyton produced by the process of repro- 
duction^ the hud may be reckoned a phyton produced by the 
vegetative process. A bud has a certain degree of vitality 
inherent in itself; and it may be called a fixed embryo^ or one 
attached to the plant, and depending for its vigour upon it, but 
frequently capable of gi'owing when separated from it." 

15. IN'ow observe what Professor Balfour says 
further : 

A tree is composed of a series of buds, each having inde- 
pendent vitality, and yet all united on a common axis, on the 
life of which they depend for their continued growth and 
vigour. Buds may be taken from one tree and grafted upon 
another, and, in some instances, buds, or bodies equivalent to 



LETTER XI. 



119 



them, separate spontaneously from plants, and form indepen- 
dent individnals. This latter phenomenon occurs in Bryo- 
phyllum^ Pinguicula^ Malaxis^ viviparous plants, and in the 
bulbils of Lilium hulhiferum^ and Dentaria hulbifera. In all 
this there is a remarkable analogy with what occurs in Com- 
pound Polyps. In Sertularian Polyps, there are numerous 
separate individuals united on a common stock, each having 
a certain inherent vitality, and yet all depending on the general 
life of the compound zoophyte." 

16. All this, you will perceive, is, with one single 
exception, in perfect harmony with what I have 
myself urged as the right view to be taken of the 
nature of trees. The exception is this : Professor 
Balfour, or perhaps I should say M. Gaudichaud (for 
Dr B. does not seem to identify himself with the views 
of the latter), says of the huds of trees, that while each 
has an independent vitality," they are all, as united 
on the " common axis," which constitutes the tree, 

dependent on the life of this axis for their continued 
growth and vigour,'' And he makes a like observa- 
tion regarding the individuals composing the compound 
animal zoophyte. How the fact may be as regards 
the zoophyte, I am not prepared to say. But I demur 
to his statement as regards the tree. I have through- 
out alleged, not merely that each bud, and each plant 
issuing from this bud, is independent of every other 
of its fellows : but that the axis " on which thev 
vegetate and grow — and that parasitically — is made 
up of the dead organic remains of the plants of former 



120 



LETTERS 0]S TREES. 



years, — in short, that the axis is destitute of vitality ; 
and that in as far as it contributes to the growth and 
vigour " of the buds and plants, it does so precisely in 
the same way that the soil does to the vigour and 
growth of the seedHng plant. And I would fain hope 
that the evidence already adduced in support of that 
allegation is sufficient and conclusive. 

17. In his work On Parthenogenesis, published some 
years ago (in 1849), Professor Owen has enunciated 
a theory as to the constitution of certain of the lowest 
tribes of animals, which accords in many, if not in 
most, of its essential features with that here unfolded 
as to the constitution of trees. And in vindication of 
his views, he has adduced like facts to those on which 
mine as to trees are based, — referring, moreover, to the 
vegetable kingdom generally, and to trees in particular, 
as being fashioned on the principle of his theory. 

18. To quote at large from this distinguished author, 
as I have done from Mirbel and Gaudichaud, would 
occupy too great a space, and be besides to travel over 
again, unnecessarily, much the same ground we have 
already trodden. In another Letter I shall have occa- 
sion to refer to his views. Meanwhile, I may observe, 
that reading his work on Parthenogenesis " shortly 
after its publication, and being struck with the simi- 
larity of many of his views to mine, I sent Professor 
Owen a copy of the essay on The Nature, Longevity, 
and Size of Trees," which I had published two years 



LETTER XI. 



121 



before, in The Edinhurgh New Philosophical Journal, 
and received from him a communication in reply, in 
which he expressed not merely his concurrence in my 
views, but his regret that he should previously have 
been unacquainted with them, — adding (and this I 
think will form a fitting conclusion to this long letter, 
and be in character with its beginning), that the 
fact of like views of the same truths springing up in 
different independently thinking minds, is one of the 
good grounds of conviction in the reality of such 
views." I am, &c. 



LETTER XII. 



" Audi alteram partem." 

February 17, 1855. 

My Dear Sons, 

1. You may remember that at the close of my 
eighth letter, I made allusion to certain exceptions 
that might be taken to my theory, and that I there 
promised to consider these exceptions in future letters. 
I purpose now to redeem that promise. 

2. One exception which I mentioned bears on a 
much agitated question in vegetable physiology — the 
nature and mode of formation of the woody layers 
annually formed in exogenous trees. M. Du Petit- 
Thouars holds, as you are aware, that the layer in 
question is none other than the roots of the buds, and 
grows if not actually yet virtually downwards from 
these to the soil. This view, I need scarcely say, 
accords entirely with the argument pursued in that 
letter — viz. that the shoots emanating from the buds 
constitute severally perfect and independent plants, 
and as such are furnished with roots. 

3. M. Mirbel, however, and otners, maintain that 



LETTER XII. 



123 



the woody layer is formed in situ, and is altogether a 
special formation. And denying to it the character 
of roots, they might ask, and so as to cast discredit on 
my theory — ''Where are the roots of those annual 
growths and alleged perfect plants in trees?" And, 
again, '' What is there in annual and avowedly perfect 
plants, at all analogous to the woody layer in exogens ? " 

4. Before discussing these questions in detail, I 
have some remarks to offer which will in fact reduce 
them to a single question — protesting, at the same 
time, that Nature is not to be tied and bound after a 
fashion of this sort. Suppose the growths emanating 
from the buds on trees to be actually destitute of roots, 
this would by no means take from them the character 
of perfect and entire plaiitSj if it could be shewn that 
the office of roots is otherwise adequately provided for. 
'' Natura ne fit per plura quod potest fieri per 
paucioraJ' On the other hand, the fact of a structure 
entering into the constitution of those growths not to 
be found in confessedly perfect annuals, — allowing this 
to be true of the woody layers of trees, would not at 
all affect their claim to be equally so regarded, if it 
could be shewn to be required either to meet some 
condition of their existence peculiar to themselves, or 
to serve some ulterior purpose in the economy of 
Nature designed to be accomplished through them. 
The mollusk is not less truly a perfect animal because 
of its wanting a bony skeleton than the mammal which 



124 LETTEHS ON TREES. 

has one ; nor, conversely, is the mammal more or other 
than a perfect animal because of its possessing such a 
skeleton. 

5. Jfow, the annual woody layer clearly subserves, 
physiologically, the purpose of a prop to the young 
plants developed from the buds — and, economically, 
that of providing timber for the supply of man's needs. 
Again, whatever may be its real nature, or however 
it may grow, it does in point of fact serve also the 
office of roots to those plants, being the channel 
whereby the nutritive matters in the soil are conveyed 
upwards to the growing stems, and leaves, and flowers. 
And since it thus serves these several purposes, the 
questions before us are, I think, fairly met and satis- 
factorily disposed of. The only question will be, whe- 
ther the woody layer is primarily of the nature of 
roots, and only secondarily intended as well for a sup- 
port to the young plants as for the production of tim- 
ber for man ; or whether it is truly a special forma- 
tion for the accomplishment of these latter objects, 
and only virtually, and by adaptation of the nature of 
roots. 

6. Reduced to this their proper issue, the questions 
before us have in reality no importance, either specu- 
lative or practical, in relation to our theory. The 
woody layer may constitute true roots, or it may be 
a special formation altogether. Be it which it may, 
the theory will be noways affected by it. Further, 



LETTER Xir. 



125 



add this other consideration, that the layer in question 
is strictly an annual formation, of the same year's 
growth with the plants proceeding from the buds, and 
equally short-lived. And with reference to this point, 
it is not a little singular that, however they may differ 
in their views as to the nature of this layer, both M. 
Du Petit-Thouars and M. Mirbel (as we have already 
seen in Letter XL) agree in regarding every tree as 
being in its nature composite, and, as such, without 
natural limit to its duration and growth. They both 
arrive at the same conclusion as to this, which is the 
main point of my theory, although they reach it in 
different ways. 

7. That the woody layer is both structurally and 
physiologically the roots of the young plants, that 
issue from the buds, I maintain. Nor will it, I think, 
be difficult to demonstrate that they are. That in the 
manner of its formation and growth there is a pecu- 
harity, I readily allow. That is to say, I allow that 
with the exception of a small portion, the fibres com- 
posing it do not actually creep and grow dowmvards 
from the base of the buds and young plants above to 
the soil below. The portion which I except is that 
part of the root beginning at the tip of the last year's 
root, and thence extending a short way beyond it into 
the soil. This portion does in fact grow and creep 
downwards, just as does the root of the seedling. 
Excepting this part, however, I admit that there is 



126 



LETTERS ON TREES. 



the peculiarity mentioned attaching to all the rest of 
it. And for that peculiarity I not only see a reason, 
but in it I see also a singularly ingenious contrivance 
Fig. 15. to obviate a difficulty which the cir- 

cumstances of trees create, and to 
meet which a strict adherence to 
the rule of ordinary annuals would 
have been a clumsy expedient. 

8. For observe : great as is the 
known power of roots in making 
their way through obstacles to the 
soil, and far as they will often tra- 
vel to reach it. it seems scarcely 
\^ conceivable that in a tree — say — 
150 feet high, and with roots 
stretching perhaps fifty feet under 
ground, the roots of the young ter- 
minal plants could, in the course of 
^ a few weeks in summer, creep down 
and traverse the distance of 200 
feet. That they do not, I admit : — 
d \\lSliH// ^ nay it is certain that they do not. 

For if they did, it would be easy 
by a few simple experiments to 
ascertain the fact, and to measure 
also the rate of their descent. 
9. Let us now consider wherein the peculiarity of 
their formation lies, and how their growth is effected. 



LETTER XII, 



127 



' The accompanying figure (Fig. 15) will aid us in the 
understanding of this. It is the vertical section of a 
tree three years old, as it exists in autumn after the fall 
of the leaves and flowers and fruit. At the summit of 
the terminal shoot, there is a bud {a), and proceeding 
from the base of this downwards, and lying between 
the bark (6 h) and the stem and root (c c) of that 
shoot, is a layer id d, d d, d d) of cells, constituting 
the cambium layer. This layer may in a certain sense, 
and that a very correct one — if not, indeed, as I be- 
lieve, truly and physiologically, — be regarded as an 
EXTENSION of the BUD, and a constituent part of it. 
Formed concurrently with the bud, and in common 
with it, out of the general cellular basis, it may like- 
wise be regarded as an adaptation of the bud to the 
special circumstances of tree-plants parasitic plants, 
and to the special objects of their existence as timher- 
producing plants. 

10. Until a comparatively recent period, the minute 
structure of this layer was but imperfectly known, and 
its real nature so far misunderstood.* It is not what 
it seems to be — a glutinous or mucilaginous fluid, — 

* " Pour nous, le Cambium est toujours le Jluide nutritif, pro- 
duit de la seve elaboree, qui s'epanche au printemps et en automne 
entre le bois et Tecorce." " Le Cambium est de fluide essentielle- 
ment nourricier du vegetal, comme le sang pour les animaux." " line 
devient pas tissu cellulaire, ni tissu vaseulaire; mais ces tissus deja 
existans y puisent les principes au moyen desquels ils se multiplient.'* 
— Richard, Nouveaux Elemens de Botanique, 6iesin.Ed. (1833), p. 111. 



128 



LETTERS ON TREES. 




or semi-fluid matter. It really consists of cells of a 

^. , ^ very delicate texture. In 

Fig. 16. *^ 

figure 16, a transverse 
section of it is given, in 
connection with a plant 
of one year's growth. 
Immediately beyond the 
woodv bundles already 
formed {a a), there lies a 
mass of cells of a semi- 
lunar form (6 6), cut off, 
so to speak, by a bounding 
line from those bundles on the one hand, and from the 
general cellular basis on the other. These cells are 
that part of the Cambium-layer out of which the 
woody bundles of next year will be evolved. Lying 
directly beyond and around these semi-lunar masses 
of cells, is the remainder of the Cambium-layer, con- 
sisting likewise of cells. 

11. Such is the condition of the tree in Autumn, 
and such the provision made for the growth of next 
year's tree-plants. In spring, the bud, growing in the 
first instance at the expense of the pith, sends out a 
shoot, which rises upwards and puts forth leaves ; sap 
ascends from the soil and passes to the leaves. Being 
there elaborated, a portion of this sap again descends, 
in order to the development of the Cambium-layer. 
From all that portion of this layer that as yet exists 



LETTER XII. 



129 



(and which extends from the summit of the last year's 
shoot to the extreme point of last year's root), there 
is ultimately evolved three distinct tissues — woody 
tissue, cellular tissue, and bark tissue, — the bark lying 
outside and enclosing the other two, the cellular con- 
necting the wood and the bark. Grant that all these 
are formed as they lie {in situ.) It is not, however, 
the whole account of the matter. For, from the lower 
end of the Cambium-layer, — at the point where it is in 
contact with the tip of last year's root, a new root 
comes off which does in fact creep doicniuards^ — which 
descends into the soil, just as from the bud at the other 
end of the Cambium-layer the shoot ascends into the 
air. 

12. We shall presently consider in what way the 
transformation into woody tissue of the intermediate 
(and far greater) portion of the Cambium-layer is 
effected. Meanwhile, let us compare what has just 
been described as occurring in the tree with what 
occurs in the seedhng plant. We shall see that the 
analogy between them is as complete as possible. 
From the embryo contained in the seed, there passes 
upwards the shoot, and downwards the root — the 
shoot and the root being united at a point called the 
neck. In like manner, from the summit of a tree 
fifty years old there rises upwards a new shoot, and 
from its opposite extremity in the soil there passes 
downwards a fresh root — separated, however, the one 

I 



130 



LETTERS ON TREES. 



from the other by the persistent stems and roots of 
the intervening fifty years' plants. Now, in order to 
connect them, or rather in order to bring the base of 
the root into direct relation with the base of the shoot, 
the expedient of a Cambium- layer is resorted to ; and 
in striking accordance with the general analogy of the 
seedling, the tissues into which that layer is trans- 
formed are identically of the same nature with the 
root. Thus is the root hfted up, as it were, to the 
base of the shoot or stem. 

13. It will perhaps enable you the better to under- 
stand what I have now said, if I observe that there is 
no natural line of demarcation, and, in point of fact, 
no structural difference between the woody tissue 
above-ground, forming what is called the trunks or 
wood proper, and the woody tissue under-ground, 
forming what is called the root; and that if we are 
to adhere strictly to the proper meaning of the terms 
stem and root^ we must restrict the one to those parts 
of the mass above-ground which have, year by year, 
actually grown and risen upivards^ and the other to 
those parts of the mass under-ground which have 
actually grown and crept downwards. We should 
thus have nothing more than the bare skeleton repre- 
sented in the vertical line of Figure 17, — the parts 
marked 1, 2, 3, being the stems, and those marked 
1', 2^ 3', being the roots, — while the side parts, marked 

a, hb, and a^a', 6^6', which represent the woody 



LETTER XII. 



131 



Fig. 17. 



tissue of the far greater part of the Cambium-layers 
(and which give strength and 
stabiHty to the stems and 
roots, and preserve them 
from decay), would be en- 
tirely accessory, and would 
require some proper name 
common to the portions both 
above and below ground. 
At all events, as regards 
this whole mass of ligneous 
tissue, whatever name we 
may give it, it is one and 
the self - same structure 
throughout, and identical in 
its character with true and y_ 
genuine roots. 

14. With regard to the 
transformation of the Cam- 
bium-layer, it is effected 
after this manner : Such of 
the cells composing it as 
are destined to become cellu- 
lar tissue merely, undergo no particular change beyond 
a full development, and that in the transverse direc- 
tion of the axis of the tree. Those of them, on the 
other hand, that are to form woody tissue, undergo 




132 



LETTERS ON TREES. 



an elongation in the vertical direction (on one side or 
on two opposite sides), and thus elongating become 
fusiform or spindle-shaped fibres. These cells have 
likewise a peculiar tendency to the production within 
their substance, or on their inner surface, of a consoh- 
dating deposit, to which they owe the tenacity and 
toughness which gives to wood its value. Their elon- 
gation, according to Dr Carpenter, does not seem to 
be the result of pressure, but of the unequal nutrition 
of different parts of the cell-wall.* Whether each 
individual cell is drawn out to any considerable extent, 
or whether a number of them coalesce to form a single 
fusiform fibre, does not yet appear. Neither is it 
known whether the individual fibres join end to end 
together, and so form continuous threads of great 
length. But we shall see by and by that some such 
union and coalescing of cells and fibres must needs 
take place. And we shall see also that there is a good 
deal more in this part of the process of transformation 
than has yet been unfolded even in our more recent 
treatises on vegetable physiology. Certain it is that 
the whole account of the matter is not ended by saying 
that the tissue in question is formed in situ and by an 
elongation of the cells. 

15. That this tissue is really of the nature of roots, 

* Principles of Physiology, General and Comparative, 3d ed., 
p. 99. 



LETTER XII. 



133 



by which expression I mean identical in every respect, 
structurally and physiologically, with roots, is to my 
mind as plain as anything can well be. In my next 
Letter, I shall endeavour to make it as plain to yours. 
— I am, &c. 



LETTER XIII. 



Truth proposed is much more easily perceived, than without 
such proposal it is discovered." Archbishop Secker. 

March 29, 1855. 

My Dear Sons, 

1 . I proceed, as proposed in my last letter, to con- 
sider the evidence in favour of the assumption that 
the vroody tissue evolved from the Cambium-layer is 
of the nature of roots. 

2. And the first consideration which I shall urge is 
this, — that, whenever the circumstances of the Cam- 
bium are such as to admit of it, the tissue developed 
from this layer palpably assumes the character, puts 
on the aspect, and grows after the manner of roots. 
Take, for example, the process of slipping." You 
cut off the upper part of the young shoot of a willow, 
to which is attached a bud, and you plant it in the 
ground. In due time the bud sprouts, and from all 
that part of the Cambium which is in immediate con- 
tact with the soil, genuine roots are given off, such as 
will be given off from the Cambium in the parent 
tree, at the tips of the last year's roots, and nowhere 



LETTER Xlll. 



135 



else — the corresponding portions of that layer in the 
shoots that remain in connection with the tree being 
all converted into " wood," The like occurrence takes 
place in the process of propagation by layers." A 
branch of a tree is turned down, and part of it placed 
under ground. From the whole of that portion of the 
Cambium of the branch which is thus brought into 
relation with the soil, and which, under ordinary cir- 
cumstances, would have been transformed into ''wood," 
true roots come off. 

3. Again, consider what is presented to our view in 
the Elm at North Stoneham, to which I formerly 
referred. Read again what I said in my ffth letter 
(section 9) respecting it; and consider this further, 
that from all that portion of it which was cut or torn 
and brought into contact with the air — and which was 
left unsupported and unfettered by the cellular tissue 
— the Cambium-layer sent down fibres and bundles of 
fibres, the radicular character of which is beyond all 
question. In a little volume, entitled The Book of 
Trees^^ another example of the like kind is described 
and figured as it presented itself in an old Oak on the 
banks of the Wear, a few miles from Durham. In 
this case, the roots that were sent down from the 
upper part of the decayed bole, not only made their 
way down and struck into the ground; but being 
cabined and confined within the chasm which they 
* Published by J. W. Parker : 3d ed. Pp. 30, 31. 



136 



LETTERS ON TREES. 



occupied, seemed to grow together and coalesce, com- 
pletely filling up this chasm, and ultimately presenting 
all the characters of wood — or at least giving to the 
once decayed Oak the aspect of a sound and entire 
tree. 

4. Mr Jesse, in his Gleanings in Natural History, 
gives two instances of the like occurrence — the one in 
an Oak, the other in an Alder ; and Professor Balfour, 
in his Class-Book of Botany (p. 446), refers to two 
others — the one in a species of Willow {Salix vimi- 
nalis) near Sleaford, in Lincolnshire ; and the other in 
a large specimen of Mountain Ash at Prestonhall, 
near Edinburgh. Mr Jesse's account of it in the 
Alder is so much to my present purpose that I quote 
it entire. Some years ago, I remarked an old Alder 
that seemed to have been decayed and hollow for a 
great length of time, and I observed from a flourishing 
branch in the upper part of the tree a sort of roots 
coming down, as if in search of the earth for nourish- 
ment. Mr Nicholson and I have frequently visited 
it, and found that the roots crept down the hollow 
amongst the decayed wood till they reached the 
ground ; and there deriving nourishment, swelled, 
united, and became as the bole of the tree, filling up 
the cavity, and displacing all the mouldering wood 
till the whole is now nearly a solid tree." And Pro- 
fessor Balfour's account of the Mountain Ash at Pres- 
tonhall might stand for a literal description of the Elm 



LETTER XIII. 



137 



at North Stoneham. " A large branch was broken 
off, laying bare the interior of the stem to a consider- 
able extent. The tree still lived, and from the upper 
branches distinct roots were sent downwards, which 
gradually covered a large portion of the wound. The 
growth was traced in a downward direction, and the 
root-like appearance of the fibres was quite evident." 

5. Further, examine carefully the naked trunk of an 
Oak, or other hardwood tree, which has been felled 
and stript of its bark, particularly after it has lain some 
time exposed to the weather. Look at the general 
course and disposition of the fibres, and particularly 
at the way in which they comport themselves where 
the main branches join the trunk, or where two 
branches meet, or in the neighbourhood of hollows 
or clefts ; and I think you will be satisfied that I 
spoke truly in my last letter (§ 14), when I said, that it 
is by no means a full account of those fibres to describe 
them as formed in situ, and evolved by an elongation 
of certain of the cells of the Cambium-layer. Were 
this all that could be said of them, we might expect to 
find the fibres disposed in tolerably straight lines and 
perpendicularly to the axis* But what do we actually 
see ? We see the fibres, as a whole, pursuing a spiral 
course downwards — winding round the trunk ; — mean- 
dering, however, and twisting in all directions in their 
course to the ground, — turning round knots or other 
obstacles that lie in their way — even ascending to steer 



138 



LETTERS ON TREES. 



clear of them and then creeping round them ; often, 
besides, without apparent reason, reyersing their 
course, again returning upon themselves, and form- 
ing chicles, or portions of circles, or duplications of 
various sorts and shapes ; and after resuming their 
usual oblique or spiral direction downwards, again 
going through the like evolutions. 

6. Attentively examining such a piece of timber, 
and observing that singular disposition — and as one 
may say, those strange vagaries of the fibres, one 
cannot help identifying those fibres with roots, or 
regarding the whole as a mass of roots." Less free 
to do so, they yet disport themselves as roots do. — I 
have said that in many trees, the fibres run as a whole 
in a spiral direction round the trunk — not in straight 
lines downwards ; and there is this further peculiarity, 
that individual sets of fibres which form part and 
parcel of branches stretching in one direction — say 
to the south, may often be traced, as they make their 
way down, gradually to wind round the trunk and 
pass under ground into a division of the root" which 
strikes in a direction directly opposite. The final 
cause of this is obvious enough, — the physical cause 
probably beyond our reach. It looks as if the fibres 
were actuated by a sort of instinct, and were led 
thereby to arrange themselves in the manner best 
adapted to enable the entire tree, or particular parts 
of it, to sustain the superincumbent weight, and 



Vl-y. 18. 




TEW-TKEE. 



LETTER XIII. 



139 



effectually to resist the agency of wind and storm. 
This at least is manifestly the effect of the arrange- 
ment, and is doubtless in part the intention of it. 

7. Other and more striking illustrations of the view 
here taken of the nature of the woody layers and 
their constituent fibres, are furnished by such trees as 
assume a columnar disposition in the bole or trunk, — 
and of which we have examples in the Thorn, the 
Lombardy Poplar, the Birch, the Beech, but perhaps 
best of all in the Yew. Look at the wood-cut facing 
you. It is the portrait of an old Yew-tree standing 
by a Church, — a locality in which such Yews are 
oftenest to be met with — not, by the way, that they 
were originally planted near Churches, but because 
in the olden time Churches were often planted near 
them. What, let me ask, strikes you most on looking 
at the trunk of this tree ? Is it not that it consists of 
one entire mass of roots — the several bundles being 
most curiously plaited together, and inextricably 
interwoven ? 

8. There is a singular fact mentioned by Mr Jesse 
respecting the Thorn, which may be regarded as an 
extreme degree of the grouping which is so manifest 
in that Yew, and which goes far to demonstrate the 
actual identity between the " trunk'' and the root" 
of trees. You may remember that in one of my 
earlier letters I remarked, that, however the woody 
fibres may keep together in the trunk, and give to 



140 LETTERS ON TREES. 

this an aspect of its own, they no sooner reach the 
ground than they part company, and spread hither 
and thither. Now, when the Thorn has become old, 
the trunk in some way breaks up into separate stems, 
— some Thorns, Mr Jesse tells us, having four, or five, 
or even six stems, which were originally one, — and 
these stems, as they separate, become regularly barked 
round, forming to appearance so many distinct trees 
closely planted together, except that they all meet at 
the butt of the tree." Mr Jesse mentions that some 
of the Thorns in Bushy Park are now undergoing 
this process of separation, having already thrown out 
one stem, while in other parts they are deeply indented 
with seams down the whole stem. These gradually 
deepening (he adds) from opposite sides towards the 
centre, will at last split the tree into a number of 
separate stems, which are barked round." * 

9. There is yet another fact bearing on our present 
subject which demands very special consideration. 
Under ordinary circumstances no fibres can be seen 
creeping down from the base of the buds in trees. 
The fact is, or seems to be, that, under such circum- 
stances, the bud has no need to do so. It is done for 

^ Gleanings in Natural History, p. 89. The resemblance which 
this process of separation in the Thorn bears to the woody bundles 
in the Yew is also pointed out by this writer. " The Yew-trees I 
have observed are sometimes strongly marked with seams, especially 
those which have arrived at a great age ; but I have not seen any 
in which the separation has actually taken place," 



LETTER XIII. 



141 



it by the Cambium, whose proper office it is to provide 
the roots. The two forming but one body — the Cam- 
bium being but an appendage to the bud — each exerts 
its own innate tendency ; and, while the bud sends up 
the shoot or stem of the plant, the Cambium-layer (or 
that particular portion of this which stands imme- 
diately related to that particular bud) evolves the 
root — superseding thereby the necessity of any effort 
in this direction on the part of the bud. That the 
bud, however, is capable of successfully exerting itself 
in this way appears from what is represented in the 
adjoining figure (Fig. 19), as Fig. 19.* 

occurring in the Dracoena ; and 
likewise from a circumstance 
mentioned by M. Richard. He 
states that he had seen in the 
possession of M. Du Petit- 
Thouars, a branch of Rohinia 
pseudo-acacia on which Rohi- 
nia hispida had been grafted. 
The stock had died ; but the 
graft had continued to grow 
notwithstanding. And thus growing, it had given off 
from its base a sort of plaster (une sorte d'empate- 




* Truncated stem of a Dracoena after maceration, shewing the 
radicular woody fibres of the branch (r) overspreading a portion of 
the stem (/) • *5 tracheae of the stem and branch. — From 

Balfour's Class-Book of Botany, p. 447. 



142 LETTERS ON TREES. 

ment), formed of very distinct fibres, which surrounded 
the extremity of the stock to some distance, forming a 
kind of sheath. It was quite easy to perceive that 
fibres had proceeded from the base of the graft, and 
had spread themselves over the stock.* 

10. Here the stock had died. There was no living 
Cambium-layer to unite with the bud of the graft; 
and as this bud lived and continued to grow, it had no 
help, so to speak, but to push out and send down roots. 
No doubt the instance given by Richard is altogether 
a rare one. It is but very seldom that a graft will 
under such circumstances hold. But it is not on that 
account the less valuable in relation to my argument.f 

11. But what is a rare event with the bud of the 
Exogen, and a singular phenomenon when it does occur, 
is the rule and order in that of the Endogen. The 
terminal bud of the Palm cut off the tree and planted 
in the ground, sends out roots. The bud of the Palm 
resting on the summit of the tree, fifty feet high, does 
the same — sending down through the cellular tissue 

* Richard, EUmens de Botanique, 5ieme Ed. p. 105 ; Lindley's 
Introduction to Botany, 4th Ed. vol. ii. p. 193. 

t In the matter of grafting, it is found to be almost invariably 
requisite that the graft and the stock should be of the same natural 
family. May not the reason be, that as the bud of the graft and 
the Cambium-layer of the stock are to be joined together in the 
closest relationship, a certain organic suitableness between them is 
part of the ordering of Nature — a suitableness of the like kind and 
involving the like principle with that which restricts the pairing of 
animals within certain degrees of consanguinity ? 



LETTER XIII. 



143 



fibres precisely similar to those which in the former 
case, it sends down into the soil. But different from 
what obtains in the Exogen, the Endogen is destitute 
of Cambium. And this difference seems to go far to 
explain the respective peculiarities in the buds of these 
two divisions of trees. But however this may be,; there 
remains the fact that the bud of the Endogen, in the 
ordinary course of its development and growth, does 
send down genuine roots within the trunk of the tree 
— which roots, in some kinds, as in the Screw Pine, 
even pierce through the trunk and ultimately reach the 
ground. And this general fact I add to the evidence 
already adduced in favour of the assumption that the 
woody layers formed annually in exogenous trees, — 
and which comprise the far greater portion of the 
woody mass both above and below ground, are in 
point of fact, physiologically and structurally, of the 
nature of roots. 

12. In maintaining that the woody tissue in the 
trunk, developed from the Cambium, is of the nature 
of roots, I have allowed that it is nevertheless formed 
in situ, or as it lies. It is impossible, however, to 
overlook the fact, so often and in so many forms 
brought under your notice, that this tissue is natu- 
rally evolved not merely in the vertical direction 
(which all allow), but in such manner that when occa- 
sion requires, it can (and seemingly without an effort), 
do that which it as naturally does at all times at its 



144 



LETTERS ON TREES. 



extreme point in the ground — viz. grow dowmuards. 
And it seems equally impossible to miss the conclusion, 
that, as evolved ordinarily in the trunk, there is more 
in the process of formation than meets the eye, — in 
short (as I remarked at the close of Letter IV.), that 
the woody fibres of the trunk — the roots of the young 
plants that issue from the buds, do virtually though 
not actually, potentially and in effect, though not 
really, grow and creep downwards. 

13. And this view has the sanction of a very high 
authority in vegetable physiology — I mean Dr Lind- 
ley. Adverting to that disposition of the fibres which 
I brought under your notice a little ago (§ 5, 6, and 7), 
as seen in the Lilac^ and in Guaiacum wood, the 
fibres in the latter crossing and interlacing," and in 
the former turning off at every projection which 
impedes them, just as the water of a steady but rapid 
current would be diverted from its course by obstacles 
in its stream," Dr Lindley observes of the disposi- 
tion in question, that it is unintelligible upon the 
supposition of wood being formed by a mere deposit of 
secreted matter." And he observes further, that if 
the new wood were a mere deposit of sach matter, 
" the latter, as it is applied to every part of the old 
wood, would deposit the new wood equally over the 
whole surface of the latter, and the deviation of the 
fibres from obstacles in their downward course would 
scarcely occur.'' * — I am, &c. 

* Introduction to Botany, 4th ed., vol. ii. p. 193. 



LETTER XIV. 



" Setting aside mere hypothesis, it seems incontestable that wood, 
in whatever manner it is deposited, is created out of organisable 
matter prepared in the leaves, or their equivalents, and therefore 
derived from them. This being so, it matters nothing whether the 
matter descending from leaves, and acquiring the condition of wood, 
be theoretically called roots, or by some other name: it is certainly 
descending matter. ''^ — Dr Lindley. 

April 30, 1855. 

My Dear Sons, 

1. The object of my last letter was to show you 
that the woody tissue of the Cambium is of the nature 
of roots — in other words, that the concentric woody 
cylinders formed annually in the trunk of the Exogen 
are none other than the roots of the plants annually 
evolved from the buds, and growing at the upper part 
of the tree. And I would fain hope that the evidence 
there laid before you in support of that view was such 
as to satisfy you that it is a correct view. 

2. The evidence, indeed, is singularly diverse. It 
is also wonderfully cumulative. When I finished that 
letter, I fancied I had said all that there was any need 
to say in that behalf. I find, however, that I had 

K 



146 



LETTERS ON TREES. 



omitted one consideration, not inferior in importance 
to anj of those then adduced. 

3. It is this : That the Cambium is wholly subor- 
dinate to the buds, and its development into woody 
tissue entirely dependent on the plants that issue from 
the buds — while, further, the degree or extent to which 
it is developed is very exactly proportioned to the 
number of the plants, the vigour of their growth, and 
their position on the tree. It is true that the Cam- 
bium cannot grow without supplies of duly elabo- 
rated" sap, and that the leaves are the organs in which 
tliis elaboration is effected. But were the layer in 
question otherivise independent of the leaves, it ought 
to grow uniformly all round the tree, without refer- 
ence to the number, or the position, or the vigour of 
the plants above. Its own inherent powers of growth 
would be equably exerted on every side, while the 

attractive" force thence resulting would ensure for 
it not merely an adequate supply, but a uniform dis- 
tribution of the nutritive materials prepared in the 
leaves. There is nothing: that I know of in the struc- 
ture of that layer, and there ought in this view to be 
nothing in its connection with the leaves, to hinder the 
freest access of the descending sap to every part where 
supplies are needed. 

4. But what do we find on examining the concen- 
tric woody circles ? Look again at the adjoining 
figures, to which I formerly directed your attention, 



LETTER XIV. 



147 



Fig. 20. 



and say whether the circles be not singularly eccen- 
tric ? Not only do we see the circles of different 
years of very 
different thick- 
ness, but diffe- 
rent sides — dif- 
ferent portions 
or segments of 
the same circle, 
widely different 
in that respect. 
Now, what I al- 
lege is, that all 
this is very ex- 
actly propor- 
tioned, as before 
observed, to dif- 
ferences in the 
number and po- 
sition of the 
plants growing 
on the tree, and 
likewise to dif- 
ferences in their 
vigour, as influ- 
enced by situa- 
tion or expo- 
sure, and by the 
character of the seasons 



Fig. 21 




148 



LETTERS ON TREES. 



5. Take a tree, for example, from the middle of a 
plantation of Firs, thickly set together — in which part 
the trees grow only at the top, and rise up as bare, 
narrow poles — and compare its woody cylinders with 
those of another tree taken from the outskirts of the 
plantation, where the side plants of the trees as well 
as the vertical have had full scope. Compare, again, 
the circles in a tree taken from the south side of such 
a plantation with those in a tree taken from the north 
side. Carry the comparison a step farther, and note 
the differences between the circles in any one or all 
of these trees and those of a Fir of the same species 
that has grown by itself in an open but well sheltered 
park, where it has had room to grow freely, and to 
spread in all directions. If the Cambium-layer be 
essentially an independent structure, and possessed of 
innate powers of growth, whence the differences, which 
you cannot fail to perceive, in the thickness of the 
woody layers, and whence the uniformity in the rela- 
tion which they bear in that respect to the amount 
and to the character of the vegetation going on above? 
The legitimate inference from the facts, and the pro- 
per answer to the questions, is, that the Cambium-layer 
is not an independent tissue, but one subordinate to 
the buds, and that it is ill or well developed, equally 
all round or partially here and there, and differently 
in different years, just because it is virtually the roots 
of the plants that come of the buds, and because the- 



LETTER XIV. 



149 



fibres of these roots are regulated as to their amount 
and distribution by the number, and disposition, and 
quahty of the plants. 

6. Nor is this all. The crowning argument for the 
subordination of the Cambium to the buds, and for its 
absolute dependence on these for its transformation 
into woody tissue, — and that in a way altogether 
irrespective of supplies of nourishment, is furnished 
by one or two very simple experiments, which leave 
those supplies intact. Cut off in spring, before the 
process of vegetation is begun, all the buds from 
one of the branches of a tree ; and at a later period, 
but in the early part of summer, cut off all the leaves 
from another branch of the same tree, — leaving how- 
ever the buds and leaves of the other branches un- 
injured. In the one case the transformation of the 
Cambium into wood will he prevented, — in the other, 
the further transformation of it into wood will be 
arrested^ — while the buds and leaves of all the other 
branches being left to grow, the Cambium-layer in 
every other part of the tree will be duly developed. 
It is difficult or impossible to understand why this 
should be, on the supposition that the Cambium- 
layer is an independent structure, and no farther 
dependent on the leaves for its development than 
as these effect the requisite changes in the sap. It 
is true that the mutilated branches receive no sap 
from the time they are deprived of their buds or 



150 



LETTERS ON TREES. 



leaves. But the effect of the mutilation, on their 
Cambium, cannot be owing merely to this privation, — 
because nothing need hinder it from drawing the 
needful supplies from the adjoining branches. It is 
easy, however, to understand it on the supposition 
that the Cambium is only an extension of the buds 
and the matrix of the roots of the plants that issue 
from the buds. Take away the buds, or take away 
the young plants themselves : you deprive the Cam- 
bium of the only office it has to serve ; and, doing this, 
you destroy its capacity of growth. 

7. One thing I must add, not to qualify what has 
just been said, but to obviate misapprehension. It 
might chance to happen that from the sides and 
through the bark of a branch thus mutilated, shoots 
would sprout, and the Cambium-layer be in con- 
sequence more or less transformed into wood. But 
this would be an instance not of the Cambium exerting 
independent powers of growth, but of buds inter- 
spersed here and there through its substance pushing 
out. The Cambium-layer of many kinds of trees, the 
Elm in particular, is thus furnished with buds over its 
whole extent. Under ordinary circumstances these 
buds commonh remain " latent " or dormant," — - 
and that because of the divergent influence resulting 
from the development and growth of the proper buds. 
Independently of this, in some trees, these Cambium- 
buds push out every season, concurrently with the 



LETTER XIV. 



151 



other buds, although from the cause mentioned 
their shoots are small or but imperfectly developed.* 
The phenomenon is best exhibited, in those trees 
that admit of it, after the trunk has been cut 
close to the ground, when large and vigorous " suck- 
ers " spring from the stump, and even from the 
roots. 

8. What passes, then, from the leaves into the 
stems and trunk appears " certainly," from what we 
have seen in this and the preceding letter, to be 

descending matter." Nor is it elaborated " sap 
merely which passes down, — but woody tissue also. 
However paradoxical it may seem, this tissue is at once 
formed in situ and by growth downwards. Ordinarily, 
it does not actually creep downwards from the top to 
the bottom of a tree. It has no need to do so. Yet 
even then it does so virtually. And when occa- 
sion requires or opportunity offers it does so in 
reality. Let me recall to your recollection the leading 

* These Cambium-buds commonly undergo imperfect develop- 
ment — often evolving externally little else than leaves or leaflets, 
but reproducing themselves and vegetating year after year at the 
same points, give rise to nodosities or swelUngs (v^hich often attain 
a considerable size) on different parts of the trunk of many trees. 
I am inclined to think that a close inspection of these nodosities 
would shew that they are chiefly accumulations of woody tissue 
evolved from the leaflets of those buds; and if so, the fact would 
furnish another argument, and be a peculiarly valuable addition to 
the evidence already adduced, in favour of the doctrine contended 
for in the text. 



152 



LETTERS ON TREES. 



features of the Holly-and-chain piece (Fig. 22.) in 

my possession, which 
we have often exa- 
mined together, and 
for which I am in- 
debted to the kind- 
ness of a friend.* It 
reveals several par- 
ticulars of interest in 
relation to the habi- 
tudes of the woody tissue. The piece itself is a 
block from the trunk of a Holly-tree, within which a 
portion of chain is more or less completely embedded. 
The block had been cleft in twain after the tree was 
felled. 

9. The history of it is briefly this : — The tree inchn- 
ing, when alive and young, too far on one side, a chain 
was placed around it and firmly secured behind. In 
process of time, as the tree grew and became thicker 
— the chain being unyielding, and the pressure against 
this from within augmenting — the old bark gave way 
under the chain, and the woody fibres developed from 
the Cambium-layer grew over and enclosed it. By 
the growth-in-situ theory, the woody matter should 
merely have pushed out on either side of the chain — 
and as well below as above — and so forming an open 
gutter have left it lying there. But instead of this, 

* Alexander Hojes, Esq. of Bitterne-Grove, near Southampton. 




LETTER XIV. 



153 



it had bridged it over. And if you examine the piece 
more narrowly you will discover something more. 
On one side, you will perceive that the bridging is 
but partial : the woody matter has overlapped the 
chain but not enclosed it. Now observe the direction 
in which the overlapping occurs. It is not from 
below, but from above — the direction in which, accord- 
ing to the views of MM. Du Petit-Thouars and Gaudi- 
chaud, it might have been expected to occur. Not 
the slightest effort appears to have been made in the 
contrary direction. Nor is this all : like the Box- 
tree, figured in section 4, this Holly-tree had grown 
vigorously on one side and only feebly on the other. 
Its growth had been eccentric. And it had so chanced 
that the chain was placed around it in such manner as 
to embrace one half of each side. Now, on the well- 
favoured side, the fibres, pushing down boldly and in 
the strength of numbers, have gone right over and 
buried the chain to some depth — while on the lean or 
ill-favoured side, the resistance presented by the chain 
has been too great for them to overcome, and, accord- 
ingly, they have only partially succeeded in the effort 
— the greater number of the fibres, indeed, like a 
slowly -moving or feeble stream, having turned round 
the obstacle instead of seeking to rise over it — a cir- 
cumstance which is quite apparent on an inspection of 
the piece. 

10. In bringing to a close this branch of our sub- 



154 



LETTERS ON TREES. 



ject, I must not omit to mention that sundry specific 
objections have been advanced against the view here 
taken of the relation of the woody tissue to the leaves, 
and, likewise, against the notion of the tissue in ques- 
tion being in any sense descending matter." These 
objections are fully stated by Dr Lindley in his Intro- 
duction to Botany^'^ and are, I think, very satisfac- 
torily met and answered by him. One or two of 
them, indeed, are such as even Dr Lindley himself 
feels compelled to allow, strongly favour the view of 
the woody tissue being formed in situ. Any objec- 
tion, however, raised on this ground — that is, on the 
ground that the facts do not admit of explanation 
on any other view — may, I think, at once be met by 
the admission that in point of fact the woody tissue 
is ordinarily formed in that way, — an admission, how- 
ever, it seems to me, which does not, in the smallest 
degree, invalidate the inferences drawn from the facts 
already laid before you, as to the relation of the 
woody tissue to the leaves, or its capacity for down- 
ward growth. Instead, however, of carrying the dis- 
cussion farther here, I shall take another opportunity 
of placing before you what Dr Lindley says on the 
subject.f — I am, &c. 

^ Vol. ii. Pp. 197-201. 

f See Note A at the end of the volume. 



LETTER XV. 



" Nothing seems more difficult than to see a thing as it really is, 
imless it be the right interpretation of observed phenomena." 

Professor Owen. 

May 15, 1855. 

My Dear Sons, 

1. We have still to deal with other objections to 
our theory of trees, and these perhaps more formidable 
than any we have yet encountered. At least they are 
advanced by one, who, in rank and authority as a 
physiologist, stands second to none — I mean Dr 
Carpenter. 

2, In his Principles of Physiology, General and 
Comparative, this distinguished physiologist brings 
under his review this theory of mine — as contained 
in a paper which I published several years ago 
in the Edinburgh New Philosophical Journal; and 
he urges certain considerations which he regards 
as fatal to it. The theory itself he states so well in 
his own way that I cannot forbear here quoting his 



156 



LETTERS ON TREES. 



account of it, — and, the rather, because he gives it 
in connection with an illustration which has always 
seemed to me the happiest, as well as to furnish one 
of the strongest arguments in its favour : — 

" Another view has been suggested, which at first sight 
appears more worthy of adoption ; namely, that a tree may be 
regarded as a collection of annual plants; the buds of each 
year giving origin to those of the next, when their own term 
of existence is expired. In a potato, for example, it is argued 
that each year's growth terminates in the production of tubers 
or underground stems, which contain the buds that are de- 
veloped into distinct and independent plants in the ensuing 
season ; these in their turn giving origin to tubers, whose 
buds are to be developed in a subsequent year. Now, what 
is true of the potato, it is urged, is true of an ordinary tree ; 
the only difference being, that the remains of the previous 
growths are persistent, although dead, and that thus a perma- 
ment stem is formed, on which every generation of plants is 
developed, as it were parasitically, and to which each genera- 
tion makes an addition that is left behind when the leaves 
decay."* 

3. The other view with which mine is compared is 
one suggested by Professor Owen, in his Essay on 
Parthenogenesis, This physiologist, besides holding 
in common with myself, that a tree is to be regarded 
as not one individual, but an agregate of individuals, 
and that each series of buds should rank as a distinct 
generation'' holds also that every leaf and even 
every modified form of the same fundamental type, — 

^ 3d Edition,, p. 903. 



LETTER XY. 



157 



each sepal, petal, stamen, and carpel of a flower, is 
entitled to rank as a distinct being." 

4. Before proceeding to grapple with the objec- 
tions to my theory advanced by Dr. Carpenterj I 
cannot help giving expression to the satisfaction I 
feel that in entering the lists with a physiologist so 
eminent, I am supported by another of equal rank 
and authority, at least in this department of phy- 
siology; and that in contending in behalf of my 
favourite theory, I may have recourse, if need be, to 
the weapons lying ready to my hand in the armoury 
of Parthenogenesis, 

5. The first objection which Dr Carpenter urges is, 
that too much account is made of the leaves, and too 
little of the other parts and he adds, as exhibiting 
the force of this objection, that the leaf is by no 
means, as some have represented it, the entire plant," 
but " only the most important of the vegetative organs 
of the plant.'' f Now, I am not aware that in my 
former paper any more than in these letters, I have 
taken so exclusive a view of the bud as to have regard 
only to the leaves ; nor do I see that such a view of 
it is involved in my theory. In my own mind, the 
leaf has held no such prominency as that represented 
by Dr Carpenter. I have throughout regarded and 

* Carpenter. Ihid , pp. 901, 902. — Owen, Parthenogenesis, p. 54, 
et seq, 

t Ibid, p. 903. 



158 



LETTERS ON TREES. 



spoken of the bud " as producing stem, and root, 
and flowers, and fruit, as well as leaves, — in short, all 
the parts entering into the constitution of the most 
perfect seedhng-plant. Nor need I remind you that 
to substantiate this, — to shew that the bud is adequate 
to the production of every thing that the seed is, forms 
the burden of a large part of the reasoning in that 
paper. I then thought, and still think, that I suc- 
ceeded in doing so ; and therefore see nothing in this 
objection that is of weight or value against the theory. 
At the same time, I readily allow that in relation to 
the production of the concentric woody layers, the 
leaf is the part of the plant essentially concerned ; and 
I will, by and by, endeavour to shew, that in regarding 
it as only the most important of the vegetative organs 
of the plant, and as having for its sole ofiice that of ela- 
borating the sap, Dr Carpenter has very inadequately 
represented the character and relations of the leaf. 

6. The part of the plant, of which in Dr Carpen- 
ter's estimation too little account is made, is, the gene- 
ral cellular basis ; and it is here that the full force of 
the objection is brought out. After stating, that 
" whilst too much account is made of the leaves as 
integral components of the plant," Dr Carpenter goes 
on to say, " too little is made of the general cellular 
basis, from which the leaves originate, and which 
retains its vitality in every stem, through the whole 
period of its existence." And he adds, — 



LETTER XV. 



159 



This cellular basis is the continuous product of that in 
which the whole fabric has its origin ; it is that of which the 
leaves are offsets, developed for a particular pui'pose (the ela- 
boration of nutriment for the axis and its other appendages), 
and ceasing to exist when that purpose is answered ; and it 
retains the power of giving origin to buds from any part of it 
that may be stimulated to increased development. For al- 
though it may be quite true that, under ordinary circumstances, 
each year's growth of buds originates in the new tissue formed 
in the preceding year, yet this tissue is but the extension of the 
general cellular basis ; and, under extraordinary circumstances, 
portions of this at a great distance from the last formed buds, 
may develope a new set of foliaceous organs." * 

7. Reserving, for the present, all discussion of the 
main points embraced in the exceptions here taken, 
let us dwell for a little on one or two lesser points, 
that bear more immediately on two special circum- 
stances which Dr Carpenter adduces, in connection 
with the general statements now before you, — the 
one as positively fatal to the theory, the other as not 
in accordance with it. 

8. Admitting, which I freely do, — maintaining, 
however, that there is nothing in my theory which 
makes this admission a concession, — admitting that the 
common cellular tissue of every plant is the basis of 
the whole plant — just as a single primordial cell is the 
basis of every living being — I beg to observe that 
there are two allegations made regarding it which I 
cannot allow to pass unnoticed. Dr Carpenter says, 

* Ibid, p. 903. 



160 



LETTERS ON TREES. 



that it retains the power of giving origin to buds 
from any part of it that may be stimulated to increased 
development;" and again, that under extraordinary 
circumstances, portions of this at a great distance from 
the last-formed buds, may develope a new set of 
foliaceous organs." Now, if by these expressions 
Dr Carpenter means to assert that, under the cir- 
cumstances mentioned by him, buds and leaves may 
be developed at a great distance from any part of the 
new Cambium-layer, contiyiuous with the last-formed 
buds, and of the same year's formation with them — 
in short, from the old cellular tissue of bygone years, 
I demur to the accuracy of the statement. And we 
shall presently see that the Elm," which he instances, 
gives no countenance to it. Again, he says of this 
general cellular basis, that " it retains its vitality 
in every stem through the whole period of its exist- 
ence'' There is a mischievous ambiguity here, cal- 
culated to mislead and perplex you. The statement 
is true in a certain sense, but not in a sense that 
affects the argument pursued in my ninth letter, or in 
the slightest degree touches the theory. The con- 
tinned vitality of the whole cellular tissue of every 
stem, is none other than the continued vitality of the 
hair of your head or the nails of your fingers and 
toes; and which, except at the points in immediate 
and very temporary contact with the skin where they 
are actually growing, and " of which they are offsets, 



LETTER XV. 



161 



developed for a particular purpose," possess no more 
vitality than those portions of them which, from time 
to time, for your particular convenience and comfort, 
you pare or crop. That it is in this sense and no 
other that Dr Carpenter does or can speak of the 
continued vitality of the general cellular basis, may 
be inferred from his known views as to the very 
transient duration of vitality in any organised struc- , 
ture. And that it is, is clear from a more specific 
statement which he makes in regard to trees : — 

"There need not be the least difficulty in admitting the 
continued vitality of the general cellular basis of the stem of 
an ordinary tree, notwithstanding that it may have attained 
the age of some hundreds, or even thousands of years. The 
parts Jirst formed may have long since decayed away^ but a 
new growth is continually taking place." * 

9. I mentioned that, in connection with the general 
statements now before us, Dr Carpenter adduces two 
specific instances in opposition to my theory. Let us 
see whether they embrace anything not contained in 
those general statements. The first is that of an 
Elm :— 

An Elm- tree, which grew to the height of nearly thirty 
feet before it gave off any branches, had its upper part entirely 
broken off in a gale of wind, and the stem was left standing, 
entirely bare of foliage. Its death was considered almost 
inevitable (and such it was upon Dr Harvey's theory ;) but it 
was thought desirable to give it a chance of recovery, and 

* Ibid. p. 904. 
L 



LETTERS ON TREES. 



nothing else was done than to slope off the top of the stump, | 
so as to prevent the lodgement of rain. The next spring a 

great number of buds were developed, along nearly the whole ' 

ength of the sturap, where no buds or branches had grown ^' 
for many previous years; these, in process of time, became 

branches ; and the topmost branches having gradually changed (x 

their direction (in accordance with the well-known law) from j[ 

the horizontal to the perpendicular, now appear like continua- ,| 
tions of the stem ; and the tree, after an interval of about 
twenty-seven years, has quite recovered its symmetrical appear- 

ance, although its aspect is of course very different from that I 

which it presented before the accident." * u 

10. If it be maintained by Dr Carpenter, that, in | 
this instance, the buds which were developed, the " 
spring following the accident, along nearly the whole ' 
length of the stump, proceeded from the general ^ 
cellular basis of an older date than the Cambium- " 
layer formed the year the accident occurred, it may 
be asked on what grounds he forms his opinion. ' 
Nothing appears in the narrative to make it even 
probable that they did so. If, however, it be admitted 
that the buds proceeded from the Cambium-layer of 
the same year's formation with themselves, a very few 
considerations will, I think, serve to shew that this 
Elm proves nothing against the theory. Agreeably 
to this theory, the Cambium-layer is the source or i 
matrix of the roots of the plants which emanate from 
the buds. Now, observe first of all what Professor 



* Ibid. pp. 90S-4. 



LETTER XV. 



163 



[Balfour says regarding roots : — Roots have no 
proper leaf-buds ; but in certain circumstances they 
are capable of producing them."* This statement 
seems to me to furnish a sufficient explanation of what 
occurred in the Elm, and to be a sufficient reply to 
the objection founded upon it. Let me observe fur- 
ther, however, that of the many different sorts of 
trees, in none perhaps is the capacity mentioned by 
Dr Balfour greater than in the Elm. It is matter of 
notoriety that growing naturally and entire, it con- 
tinually throws out branches along almost the whole 
length of the trunk, and to such an extent often, as to 
present one unbroken mass of foliage from the ground 
to the summit of the tree. Moreover, the reduction 
of the Elm to the condition to which the gale of wind 
reduced Dr Carpenter's, is daily practised with a view 
to the propagation of it by grafting. " The mode 
of propagation resorted to in the case of the English 
Elm is usually by means of suckers from the parent- 
tree. And the best description of suckers are those 
which are produced by trees that have been cut dose 
to the ground."! short, to any one at all familiar 

Class-Book of Botany, p. 52. Roots in point of fact produce 
buds oftener and more generally than would appear from Dr Bal- 
four's statement. Only under ordinary circumstances, i. €» from 
the divergent influence of the vegetation going on in the branches 
at the further end, they remain "latent" or "dormant." — (See 
Letter XIV. § 7.) 

t Book of Trees (J. W, Parker), 3d ed. Pp. 137-8. 



LETTERS ON TREES. 



with the habitudes of the Elm, the death of such a 
tree from such an accident as that mentioned by Dr 
Carpenter, need not have been considered almost 
inevitable." It would not have been so considered by 
the patriarch Job : — " There is hope of a tree, if it be 
cut down, that it will sprout again, and that the tender 
branch thereof will not cease. Though the root thereof 
wax old in the ground, and the stock thereof die in the 
ground ; yet, through the scent of water, it will bud 
and bring forth boughs like a plant."* 

11. The other instance is derived from the struc- 
ture and constitution of the Cactaceoe : — 

" The doctrine in question is entirely inapplicable to the 
case of the leafless Phanerogamia, such as the Cactacece. The 
succulent mass of which their stems are composed, is obviously 
homologous with that general cellular basis, of which the axis 
of all the higher plants consists at an early stage of their 
development, and from which the leaves are developed where- 
ever they exist; whilst its foliaceous surface performs the 
functions of the leaf, the two organs not being here separated, 
nor their functions specialised. Now, it cannot but be ad- 
mitted, that it is this cellular mass which in the Cactace^ 
constitutes the plant; since here no separate leaves are evolved. 
And further, we must regard the whole as one integer, unless 

* Chap. xiv. 7, 8, 9. — The French rendering of the last clause 
(ver. 9) whether more paraphrastic than ours or not, probably 
better expresses the idea present in the mind of the writer, and is 
certainly more in keeping with the quotation just made from the 
Book of Trees : — " Des qu'il sentira Feau, il regermera et produira 
des branches, comme un arbre nouvellement plante." 



LETTER Xy. 



165 



we are prepared to say that every separate portion of this mass, 
f^hich can maintain an independent existence, is to be regarded 
is endowed with a distinct individuality, i^ow, the duration of 
;his cellular stem of the Cactace^ is extremely prolonged, its 
ife being very slow ; so that there are undoubted instances of 
slants of this order continuing to exist for 100 years ; and 
:heir probable term of life is very much longer." * 

12. I can see nothing in what is here said regard- 
ng the CactacecB at all at variance with my theory. 
But I see much which, on the principle of Exceptio 
urohat regidam," goes to give support to it. The 
constitution indeed of the Cactus is less complex, — 
that is to say, it contains fewer distinct parts than 
Drdinary plants, and, in particular, it is destitute of 
iistinct and ordinarily constituted leaves. But, ob- 
serve, whatever be the special object of its existence, 
it is plain that it was not made for the production of 
timber. And accordingly, whatever other reasons 
there may be for the simplicity of its structure, — and 
while it has in the foliaceous surface of its succulent 
stem just that sort of leaf which performs the only 
office that this plant needs, viz. the elaboration of 
sap, — it has not that sort of leaf which is required for 
that other office which (as we have already seen and 
shall see again by and bye) the leaf serves to timber- 
producing plants, to wit, a leaf in itself distinct and 
special, possessed of ligneous tissue, and, in some way, 



* lUd, p. 904. 



166 



LETTERS ON TREES. 



directly or indirectly, itself producing or essentially 
contributing to the production of the ligneous tissue 
of the woody stem. As for the rest, the Cactus grows 
and extends itself in the same way as trees do, — by 
buds; and the individual growths that issue from 
these buds are I presume equally short lived, indi- 
vidually, as those from the buds of trees. Dr. Car- 
penter, it is true, speaking of the aggregate stem, 
remarks that its duration is extremely prolonged, its 
life being very slow. But I fancy the remark is to 
be taken in the same sense with that formerly ad- 
verted to in this letter. 

13. As far then as these two instances go, I see 
nothing in Dr Carpenter's strictures that militates 
against my theory — nothing at least that is not em- 
braced in his general statements — to the considera- 
tion of which I shall proceed in my next letter. — I 
am, &c. 



LETTER XVI. 



" And darest thou then 

To beard the Lion in his den, 
The Douglas in his hall ?" 

Sir Walter Scott, Bart. 

Maij 28, 1855. 

My Dear Sons, 

1. My last was an affair of outposts. We have 
now to do battle with Dr. Carpenter's main army, 
drawn up in two divisions — a right and a left. We 
shall in the first instance engage the former, — 
and routing it (as I hope we shall), next try our 
strength against the latter — to all appearance much 
the more formidable of the two. Let us first of all 
see what the enemy's forces are, and how they are 
disposed. 

2. Dropping, now, this way of speaking, let me 
observe that the leading arguments advanced by 
Dr Carpenter in opposition to my theory, may be 
described as embracing two parts. The first is that 
which will alone occupy our consideration in this 



168 



LETTERS OX TREES. 



letter ; but it will be conyenient before entering on 
the discussion, to put you in possession of both 
branches of the argument. The former I laid before 
you in section 6 of my last letter — which section I 
must beg you will now turn to and carefully read 
over. The latter is as follows : — 

" There appears, then, to be no medium between, on the one 
hand, regarding the entire fabric developed from a single genera- 
tive act (z. e., the fertilisation of a single ' germ-cell' by the con- 
tents of a ' sperm- cell ') as forming one organism^ however great 
maybe the multiplication of similar parts, or however indepen- 
dent these parts may be of each other ; and the inckiding every 
product of its own development, whether contemporaneous or 
successive, as one generation; or, on the other hand, attributing 
a distinct individuality to every component of the most com- 
plex organism, and designating every augmentation of the 
number of its cells, by the subdivision of those previously exist- 
ing, as the production of anew generation."* 

It is but fair to Dr Carpenter to subjoin what he 
further adds : — 

In either case, it must be freely admitted, we are forced 
to do a certain violence to our ordinary conceptions." "And 
it may be the wisest course, perhaps, to invent new terms, 
rather than to distort the meaning of those in common use." t 

3. Putting together, now, what I have here quoted 
and what I quoted in my last letter (section 6), and 
having regard also to certain other relative state- 

* Principles of Physiology, General and Comparative, 3d Edition, 
p. 904. 

t Ibid, pp. 904, 905. 



LETTER XVI. 



169 



ments made by him, elsewhere, in his Principles of 
General and Comparative Physiology, Dr Carpenter's 
whole view of the subject under discussion may, I 
think, be thus fairly stated : — 

First, The buds and the Cambium, together with 
the leaves and the wood and roots which proceed from 
them, if not also the flowers and fruit, are merely an 
extension (on its free side) of the general cellular 
basis, and the transformation of this basis into certain 
definite structures. And this extension and transfor- 
mation are processes which, but for certain periodic 
checks put to them, would go on uninterruptedly. 
But for these, there would neither be the breaks which 
occur in them during the winter, nor would their per- 
manent produce — the wood — present those lines of 
demarcation which we see in the so-called " annual 
layers or rings.* But for those periodic checks, all 
our trees would be evergreens ; there would be an 
unbroken succession in the formation and shedding of 
the leaves, and flowers, and fruits : and the wood 
would constitute one entire mass of ligneous and cellu- 
lar tissue, — The buds and the Cambium are merely 

continuous products " of the general cellular basis, 
evolved at the ends of the medullary rays in the case 
of the former, and over the whole exterior surface of 
the woody stem in the case of the latter ; and it is 
from those checks alone, and from no other cause, 

* Ibid, p. 790. 



70 LETTERS ON TREES. 

that an interrupted character is given to their evolu- 
tion, and a seasonal aspect imparted to their develop- 
ment — which, however (striking as it is), denotes, after 
all, merely an epoch " in their vegetation.* And, 

Secondly^ In accordance with these views, Dr Car- 
penter refuses to regard the buds and their produce, 
or the Cambium and its produce, as distinct, separate, 
or individual formations — still less as the representa- 
tives of a new generation. He refuses to co-ordinate 
the bud with the seed, or to allow to the wood the 
character of roots. And he further maintains, that 
only such an organism as has proceeded from a seed," 
itself the product of two distinct kinds of cell — the one 
a germ-cell," and the other a sperm-cell" — can or 
ouo'ht to be reo-arded as an individual bein^. 

4c These A'iews are manifestly directly opposed to 
my theory ; and, if sound, subversive of it. But they 
are, in my judgment, untenable ; and that they are 
so I will now endeavour to shew you. 

5. I begin by considering an assertion which Dr 
Carpenter makes in regard to the general cellular 
basis. And I do so, because I believe the discussion 
of it will bring out an issue that will serve as a touch- 
stone to determine whether in the main his views or 
mine are the more worthy of adoption. 

6. Speaking of the Cambium-layer, and of its being 
in a state of continual increment," he says : — The 

Ibid, p. 236. 



LETTER XVI. 



171 



proximity of leaves is not required for the growth of 
the additional layers of wood and bark into which it 
developes itself, — nothing else being needed than a 
supply of elaborated sap which may have been pre- 
pared by the leaves of remote parts of the fabric." * 
And in connection with this, let me again remind you 
of what he says of the leaves — viz. that they are 
only the most important of the vegetative organs of 
the plant," — " offsets from the general cellular basis, 
developed for a particular purpose, the elaboration of 
nutriment." 

7. Turn now to Letter XIV., and read again what 
I said there on this very point, and that without any 
thought at the time of these statements of Dr Car- 
penter's. I said, and I again repeat, that if the Cam- 
bium were an independent structure — that is to say, 
possessed of inherent powers of growth, and merely 
dependent on the leaves for supplies of duly elaborated 
sap, it is impossible to understand why the cutting off 
in spring of the buds from a particular branch (the 
adjoining branches of the tree being left entire), should 
have the effect of preventing the transformation into 
wood of the Cambium-layer of that branch, — or why 
the cutting off, in the early part of summer, of all the 
leaves of another branch (the other branches not being 
thus mutilated), should have the effect of arresting the 
further development of the layer. That the facts are 

* Ibidy p. 904. 



172 



LETTERS ON TREES. 



as I have stated, there can be no doubt. But on Dr 
Carpenter's assumption, no such results should follow 
any such mutilation of the branches, because nothing 
need hinder the Cambium-layer in either of them from 
drawing the requisite supplies of elaborated sap from 
the neiglibouring branches, or even from remote 
parts of the fabric." 

8. This single consideration seems to me to have 
all the value of an experimentum crucis, and to possess 
besides a double value. It is clearly adverse to 
Dr Carpenter's assumption ; but in the measure and 
degree in which it is so, it is favourable to mine. And 
I would beg particularly to observe, that, while (as 
before remarked) I have nowhere taken so narrow a 
view of the growths that issue from the buds as to 
have regard merely to the leaves, I think the facts 
furnished by the mutilated branches shew decisively 
that, in relation to the Cambium, the leaves are some- 
what more than organs for the elaboration of sap for 
the growth of this layer — have another office to serve 
besides this in relation to it ; — and, conversely, that 
the layer in question is beholden to the leaves for 
somewhat more than a supply of sap, and is itself 
somewhat besides a mere continuous product of the 
general cellular basis. 

9. It is true that, in a tree (a fir-tree for example) 
growing in the middle of a crowded plantation and 
growing only at the top— the lateral branches having 



LETTER XVI. 



173 



died off as the tree grew upwards, the Cambium-layer 
is duly transformed into wood eyen at its lower part, 
although this may be very remote " from the leaves 
above. In this case, however, the Cambium is in the 
direct line of the leaves, i, e. (according to my theory) 
of the plants above, and, being the roots of these, is 
of course developed. And it may serve to give force 
to this consideration if I observe, in regard to the case 
of the mutilated branches, that were the terminal buds 
merely, or the terminal leaves merely, to be left 
uninjured (all the others being stript off), the Cam- 
bium-layer would in hke manner be developed through- 
out. Nor is this all. The extent to which this layer 
is developed in the case both of the fir and the branches 
will be proportioned to the amount of the leaves ; and 
the woody layer will be thin because these are/6^^/, — 
contrasting strongly with the much greater thick- 
ness it attains in the other branches and in other 
firs similarly circumstanced, but provided with side- 
branches and laden' with foliao-e. 

10. Add to all this, what I dwelt so much upon in 
Letter XIV., and which it would be tedious here to 
repeat, regarding the varying thickness of this layer 
as transformed into wood, on different sides, according 
to the position on the tree of the several buds and 
plants, — and likewise the facts and considerations 
relative to the winding conrse of the hgneous fibres in 
most if not in all trees, — and their otherwise singular 



174 



LETTERS ON TREES. 



disposition in the Yew, the Thorn, and others, — in all 
which the development of the layer in question mani- 
festly follows a rule widely different from any included 
in Dr Carpenter's assumption. In that letter, I 
adduced the facts now referred to, and others besides, 
to shew that the ligneous fibres are none other than 
the roots of the young plants that emanate from the 
buds. And to what I there stated I may add this 
other observation, that, as regards all that portion of 
the Cambium (and of the general cellular basis) which 
retains its cellular character, and serves to warp the 
portion which is converted into wood or roots, it is 
manifestly subordinate to this portion — being turned 
aside, and in divers manners disposed of by the Hgne- 
ous fibres or roots, as they hst. 

11. One other consideration connected with this 
part of our subject seems to me too important to be 
omitted. Dr Carpenter's representation of the Cam- 
bium and buds being but ^* continuous products" and 
a " mere extension" of the general cellular basis, is 
scarcely in keeping with the fact, that both they and 
their products have as definite a character, in point of 
size and shape and form, as have the flowers and seeds. 
Further, if this representation were correct, and if 
nothing save extrinsic causes periodically checking 
the extension, gives to the produce of the buds and 
Cambium the definite character they possess, why 
should not the leaves, for example, go on growing 



LETTER XVI. 175 

and lengthening the whole season through, i. e* until 
nipped by the frosts of autumn ; and why should not 
the leaves formed the first in spring be larger and 
longer than those formed many weeks later in the 
summer? Dr Carpenter's theory will not explain 
this ; and I will make bold to say, that quite inde- 
pendently of all extrinsic causes periodically checking 
the vegetative processes, there is a definite succession 
observed by Nature in the formation of the Cambium 
and of the buds of trees, and a definite character im- 
parted to the structures evolved from them. It may 
be that, in certain circumstances and in certain 
climates peculiarly favouring the vegetative pro- 
cesses, such a succession may occur twice in one year, 
or even three times, — or five times in two years but 
each is separate from every other, and one is com- 
pleted before another is begun. And although the 
lines of demarcation between the several layers of 
wood, thus formed, may be fainter than in those of 
trees in colder climates, or even be scarcely dis- 
tinguishable, a sufficiently minute inspection of the 
woody tissue will yet demonstrate, that it nowhere 
presents an unbroken continuity of substance, — such 
a contitnuity or homogeneousness, for example, as we 
can easily discover in the woody matter of the annual 
shoot or stem. 



* Carpenter, Ibid.^ p. 790. 



176 



LETTERS ON TREES. 



12. But in Dr Carpenter's view, the bud is not 
the counterpart — the alter ego of the seed. He re- 
fuses to place the bud on a level with the seed, or to 
regard as an individual being any other than an 
organism that has come of a seed. 

13. There can be no question that every organism 
thence resulting is truly an individual. But to refuse 
the appellation to every other is, I think, physiolo- 
gically unreasonable. The distinction aimed at by 
Dr Carpenter seems to me to create greater difficul- 
ties than it can obviate ; and to violate to a greater 
extent than it can preserve, the general analogy of 
organic life. This subject, however, is too extensive 
and too important to be entered on at the close of a 
letter already quite long enough. — I am, &c. 



LETTER XVII. 



" Jusqu'a present pour nous, la vie ne nait que de la yie ; nous 
la voyons se transmettre, jamais se produire ; et quoique I'impossi- 
bilite d'une generation spontanee ne puisse pas se demontrer abso- 
lument, tons les efforts des physiologistes qui croient cette sorte de 
generation possible ne sent point encore parvenus a en faire voir 
une seule instance." — Baron Cuviek. 

" Things that are equal to the same are equal to one another." — 
Euclid. 

June 2, 1855. 

My Dear Sons, 

1. I had not space in the preceding letter to con- 
sider the last of the objections which Dr Carpenter 
urges against my theory. I wished besides, from the 
weight and importance attaching to it, to make it the 
subject of a separate letter. 

2. That objection you will remember is, that while 
the seed is the product of the union of two distinct 
kinds of cell, a sperm-cell " and a germ-cell," — 
and while the seed is the source and the representa- 
tive of a new being and of a true individual, distinct 
from its parent, and altogether independent of it, — 
the bud is but an extension," a mere continuous 
product " of the general cellular basis ; or, as he else- 

M 



178 



LETTERS OIS TREES. 



where expresses it, a mere multiplication of the cells 
of the parent by a process of continuous groivth,^ 
represents accordingly nothing more than the continu- 
ous growth of the parent, and neither in itself nor in 
its produce is possessed of any proper individuality. 

3. That this view is a mistaken one, I shall endeavour 
to shew you. 

4. In the first place, to adopt and apply to the seed 
Dr Carpenter's language regarding the bud, — what is 
the seed after all but an extension,'' a continuous 
product" of the general cellular basis ? Its involving 
the union of two distinct kinds of cell is merely the 
mode of extension adopted by Nature in this particular 
case, — not involving any principle different from that 
concerned in the bud, but merely a modification of it 
in order to the attainment of certain ends which can 
only be accomplished thereby. The seed differs indeed 
from the bud in this, that it drops when ripe from the 
parent plant, while the other continues adherent to it. 
But this is not a necessary element in the constitution 
of the bud. It obtains in the bud of the tree, because 
the purposes of Nature in the formation of trees 
require that it should. In the potato, however, and 
still more in the Marcliantia polymorplia, the Lilium 
bulbiferum^ and the Dentaria hulbifera, both the bud 
and the seed stand on precisely the same footing in 
that respect. The potato seed and the potato bud 

* Brit, and For. Med. Chir. Revievj, vol. i. p. 193. 



LETTER XYII. 



179 



germinate both of them apart from the parent plant, 
and give rise each of them to an organism which has 
no connection with that plant. 

5. Dr Carpenter's language, in fact, however well it 
may serve to convey his meaning, is expressive of no 
essential difference between the seed and the bud. It 
would serve equally well, in an argument directed 
against the doctrine of the " spontaneous generation " 
of living beings, to express the fact, that, while, as far 
as our knowledge yet extends, all living beings come 
of a germ, this germ originates in no other way than as 
an extension — a continuous product of a pre-existing 
living being. It is such language as Cuvier might 
have introduced into the beautiful passage which 1 
have placed at the head of this letter. He might 
have *said, — Jusqu'a present pour nous, la vie ne 
nait que de la vie — ' et comme une extension de la 

, vie nous la voyons se transm^ettre — ' et comme pro- 
duit continue de la vie,' — jamais se produire." 

6. In the second place, what is there in the seed 
that is not equally in the bud ? What can the seed 
evolve that the bud cannot evolve also ? Nay, the 
bud can do all that the seed can, and more. It can 
equally with it reproduce the species, and it can repro- 
duce also its own variety of the species, which the seed 
seldom does, and for which at least it can never be 
relied on. 

7. What difference is there, either in their own 



180 



LETTERS ON TREES. 



nature or in our ordinary conceptions of what consti- 
tutes individuality, between two potato plants growing 
side by side in the same garden, the one raised from 
a seed, the other from a bud ? What real difference 
between two Willow-trees growing together by the 
same water-course, the one the produce of a seed, the 
other the produce of a bud ? None certainly in those 
respects ; and only this other difference (already 
indicated), that the one will represent the species, 
and this only, while the other will represent besides 
this, its own variety of the species. But does this 
imply any fundamental difference ? Dr Carpenter 
does not expressly assert that it does, but he speaks 
as if he seemed to think it did. After observing 
that, whilst the seed " continues the species only," 
the bud " reproduces the particular variety ; " and 
that hence when it is desired to multiply a certain 
kind of fruit-tree, the buds are employed rather than 
the seeds," he adds — But this method of reproduc- 
tion cannot he carried to an indefinite extent »^ And 
for this reason, that " although it may not be true (as 
stated by some) that the life of the 'graft' will only 
last as long as that of the ' stock ' from which it was 
taken, yet it is almost invariably found that varieties 
of trees and plants which are thus multiplied lose their 
vigour and ' die out,' after a certain lapse of time."* 
8. There is I suspect a little injustice here done to 
* Principles of Physiology, Gen, and Compar., p. 901. 



LETTER XVII. 



181 



the graft in order to keep the bud in its right place " 
in Dr Carpenter's system.. The " dying-out " is, I 
apprehend, merely a reverting-back to the species^ not 
the actual death and extinction of the plant or tree, — 
the loss of that elevation in the scale of vegetation, 
which is commonly the result of '^high" cultivation, 
and which, being an accidental, or at least a superin- 
duced quality, is not so tenaciously retained as the 
primitive qualities. These, however, the bud will 
retain equally with the seed, and as indefinitely as it 
can. To say that trees raised from buds or grafts 
lose their vigour sooner than trees of the same species 
raised from seed, is, I am persuaded, incorrect as 
expressive of a general fact, and a misapprehension of 
what is occasionally seen to occur. The remark has 
reference to our common fruit-trees ; and it may be 
true that of two Apple-trees, raised, the one from a 
seed, and therefore a " Crab," — the other from a graft, 
and therefore a cultivated variety," both being of 
the same age and growing under the like circum- 
stances as to soil and situation, the Crab will last 
longer than the cultivated variety, and continue longer 
to grow vigorously. But the circumstances in other 
respects are different. The cultivated variety is a 
more prolific tree than the Crab, and bears a much 
larger fruit. And just in proportion as its vital 
energies are directed to the formation and ripening of 
a fruit which is larger and more abundant than is 



182 



LETTERS ON TREES. 



really natural^ in the same ratio will the wood and 
the bark formed by it be less perfectly developed and 
less thoroughly matured than is requisite for its full 
vigour and permanency as a tree. Its wood will be 
more perishable, and its bark less defensive ; and 
therefore external influences will the sooner and the 
more effectually act upon it to its destruction. This I 
believe to be the true explanation of the comparatively 
early decay of some or many of our fruit-trees, and of 
the observation founded on the occurrence by Dr 
Carpenter — an observation, however, which is inappli- 
cable, as a general fact at least, to the Willow, the 
Elm, and to most, if not to all of our forest-trees that 
admit of being propagated from grafts or buds. 

9. In illustration of the distinction which he draws 
between the seed and the bud, Dr Carpenter makes 
another observation which seems to me not only mis- 
applied, but detrimental to his own argument. If 
the individuality of leaf-buds be maintained, because 
they will continue to exist as grafts, the same attri- 
bute ought to be allowed to parts of animals, e.g. teeth, 
&c., which have been removed from one animal and 
implanted in another, and which have formed new 
attachments to the latter, and have continued to 
grow."* To this, it seems a sufficient answer to say, 
that the parts which he specifies have none of the 
attributes of the bud. In claiming for the bud the 
* Op. Cit., p. 902. 



LETTER XVII. 



183 



rank of a seed, I found nothing on the mere fact that 
a part of a tree furnished with a bud may be removed 
from one tree and implanted in another, and that this 
part may form new attachments to the latter and con- 
tinue to grow. I rest it on this ground, that from the 
bud there will come a plant and ultimately a tree, in 
every respect as complete and perfect as the plant 
and tree whence it was taken, and equally capable of 
producing seed after its kind as well as buds after its 
kind, and that the tree may be thus perpetuated and 
indefinitely multiplied. Nothing of this sort ever 
comes of the transference of parts spoken of by Dr 
Carpenter. But (to make the parallehsm complete), 
supposing there did. Suppose that, in the ordering 
of Nature, there should issue from the tooth of a dog, 
transferred to the comb of a cock, and growing there 
(as once there issued from a human rib a perfect 
human form), an organism so like a dog as to be undis- 
tinguishable from one, and capable of reproducing in 
the ordinary way that sort of animal, I think Dr Car- 
penter himself would be puzzled how otherwise to 
account of it than as a dog. He would not, I pre- 
sume, dispute Eve's proper individuality. 

10. I have yet two or three things further to say 
in opposition to Dr Carpenter's view. The first is, 
that if the evolution of the bud be but a process of 
continuous growth, it is one in connection with a dead 
mass. Strange anomaly, if the bud and its produce 



184 



LETTERS ON TREES, 



be but an extension and integral part of this mass ! 
An entire being alive in all its parts, growing on such 
a mass, and deriving from it at once nourishment and 
support, this one can understand. But an entire 
being alive only at its surface, and this living surface 
the continuous extension and a constituent part of a 
dead carcass, this it is very diflScult to understand. 

11. The second is, that the distinction insisted on 
by Dr Carpenter as existing between the seed and 
the bud, and of course between their respective pro- 
duce, creates far greater difficulties than it can pos- 
sibly obviate. It mystifies our simplest notions of 
individual being and of personal identity and relation- 
ship. It also invests with an unreal character — or 
rather it divests of all reality of character many of 
the noblest objects of the vegetable world, and casts 
a doubt around all of whose origin from a seed we 
have not the clearest evidence. Two stately Elms 
might be growing side by side in the same park, each 
as like the other as it is possible for two trees to be, 
and both performing exactly ahke all the functions of 
vegetable life, — and yet only one of them — and that 
by reason of its origin from a seed, could be accounted 
a real tree and a true individual ! The other, sprung 
from a sucker, would be merely the continuous pro- 
duct, and would still in fact be forming an integral 
part of another tree, all of which, save this part, may 
have long since passed away. 



LETTER XVII, 



185 



12. The third is, that Dr Carpenter's notion as to 
the bud being but the continuous product and a mere 
extension of the general cellular basis, possessed of no 
proper individuality, and as to the whole series and 
succession of parts in the same tree forming but one 
individual plant, involves this violation of the general 
analogy of organic nature, that it invests the tree 
thus regarded as one integer" with the attribute of 
immortality. It makes that true of the individual 
which heretofore we have been taught to regard as 
true only of the race to which it belongs. 

13. There is yet one other consideration, the force 
of which is to my own mind irresistible and conclusive. 
The hud can evolve the seed. This consideration in- 
ieed has already been repeatedly adduced, and is 
included in the general statement made in the earlier 
part of this letter, that the bud can evolve all that 
the seed can. But it is one which well deserves being 
dwelt upon separately, and which cannot, I think, have 
been duly weighed by Dr Carpenter. What, let me 
isk, is included in the statement that the bud can 
3volve a perfect and complete plant,— that it can 
3volve the flower and the seed ? This : that it must 
contain within itself the two kinds of cell regarded by 
Dr. Carpenter as essential to the constitution of the 
seed — as forming the essential characteristics of the 
seed, viz. the sperm-cell" and the germ-cell." — 
Dispute the force of this consideration, and, as it seems 



186 



LETTERS ON TREES. 



to me, you may as well dispute any or all of the 
axioms in Euclid. 

14. For the conclusion of this, let me just take 
notice of the danger of over-great refinements; of 
going besides or beyond the plain, obvious, first 
appearance of things.'' Bishop Butler, from whom 
I quote, makes this observation with reference to 

religion and morals." But it is equally applicable, 
I think, to our present subject. And he adds, what 
seems also pertinent to it : Persons of superior 
capacity and improvement have often fallen into 
errors which no one of mere common understanding 
couW." * No one of mere common understanding, 
I think, could make, or could well be brought to 
acquiesce in the distinction which Dr Carpenter 
draws, — and which he is compelled by his theory to 
draw, between two potato-plants, or two Willow-trees, 
or two Elms, raised the one from a seed, the other 
from a bud ; and in the face of the plain, obvious, 
first appearance of them, indicating that each one in 
its kind is in every respect the counterpart of its 
fellow, to regard the one as a real plant and a true 
individual being, the other as something altogether 
different. Such an one, too, would, I think, rather 
distrust the soundness of the theory which required 
this distinction at his hands, than admit that the 

* Fifteen Sermons,''^ Serm. Y. 



LETTER XVII. 



187 



appearances on which he grounded his behef in the 
common character of the objects were fallacious. 

15. Nay, even Dr Carpenter himself appears to 
have misgivings as to the entire validity of his objec- 
tions. For, after passing in review this theory of 
mine, and certain others more or less akin to it, and 
stating the objections to which he deems them liable, 
he concludes with an observation which seems to me 
to involve a compromise of his own views. Refusing 
to allow a proper individuality of the several products 
which come of the bud, or to regard them as repre- 
senting a new generation, he says — " It must be freely 
admitted that we are forced to do a certain violence 
to our ordinary conceptions." And it may be the 
wisest course, perhaps (he adds), to invent new terms, 
rather than to distort the meaning of those in common 
use." I need scarcely say that, in my judgment, such 
refusal is doing a real violence to those conceptions ; 
and that, in order to maintain the sole distinction 
that obtains between the product of the bud and the 
product of the seed, we need no other terms than 
those already in use, to wit, the terms gemmiparous 
and oviparous generation. 

16. That these two modes of organic genesis stand 
on precisely the same footing, in all that relates to 
the essentials of the reproductive process, seems to me 
a fair inference from the facts that have passed under 
our view. That in the seed the union of two distinct 



188 



LETTERS ON TREES. 



kinds of cell — the ''sperm-ceir' and the ''germ-cell" — 
is essential to its constitution, I readily allow. But 
were I to hazard a conjecture on a subject so obscure, 
I would say that it is essential only in reference to the 
objects intended by nature to be accomplished through 
the seed — not to the reproductive process itself. And 
I would say also, that the true original of that process 
is a si7igle cell, and this a ''sperm-cell;" — and that 
the primary seat or 7iidits of this cell is a bud^ the 
latter containing every thing (" germ-cells " included) 
that is needed for the evolution of that primordial 
cell. According to this view, the notions of our 
grandfathers and of the old patriarchs were literally 
true. Physiologically, as well as by our laws and 
the common consent of mankind, the child peculiarly 
represents the father. And St Paul was as sound in 
his physiology as in his logic when he argued that 
" Levi, who receiveth tithes, paid tithes in Abraham," 
— because, although at the time unbegotten, " he was 
yet in the loins of his father when Melchesedec met 
him," and received of him " a tenth part of all." — 
I am, &c. 



LETTER XVIII. 



" The provisions of Nature in the constitution of each individual 
of the human species are not confined to his own immediate wants : 
they extend to his adaptation for social intercourse ; to the relief 
of his sufferings by the sympathy, and the increase of his enjoyments 
by the participation of others, and to the cordial union and co-ope- 
ration of numbers in prosecuting objects and surmounting difficulties 
for which the exertions of individuals would be inadequate." 

William Pulteney Alison. 

" No sin his face defiling, 

The Heir of Nature stood, 
And God, benignly smiling. 
Beheld that all was good ! 

Yet in that house of blessing, 

A single want was known ; 
A wish the heart distressing ; 

For Adam was alone ! " 

Reginald Heber. 

" Amid Nature's infinitely diversified productions, we find but 
one original model or pattern." Dr Edward Hitchcock. 

August 18, 1855. 

My Dear Sons, 

1. In bringing to a close my argument with Dr 
Carpenter, and, with it, the whole proof and defence 
of my theory of trees, I will venture to suggest and 



190 LETTERS ON TREES. 

lay side by side of his, another view as to the mutual 
relations of the seed and the bud — the view which I 
briefly touched upon at the close of my last letter. 

2. What if the bud be the primary mode or form 
of the reproductive process, the true original and the 
proper type and representative of that process ? And 
what if the seed be but a modification of the bud, for 
the accomplishment of certain ends in the organic 
economy of Nature for which the bud is inadequate ? 
And what if that modification, although introduced 
and extensively applied, in both the vegetable and 
animal kingdoms, long anterior to the creation of man, 
were introduced at the first with a prospective refer- 
ence to him, and have its root in him, — its primary 
source in man's moral nature, and its true significancy 
in the institution of marriage, and in the family and 
social relationships of humanity ? 

3. There seems nothing unreasonable in this view, 
while there is much in the historv of this earth, in 
what we see around us in the world, and indirectly in 
the teaching of Revelation, to give countenance to it. 

The Heavens are the Lord's, but the Earth hath He 
given to the children of men." Teeming though it 
be with countless mvriads of innumerable kinds of 
vegetables and animals, this earth has yet been cre- 
ated for man. It has been the scene of many suc- 
cessive and progressive changes extending over vast 
periods of time — in all probability over millions of , 



LETTER XVIII. 



191 



years — to make it a fit habitation for him. And 
changed yet once more, as we are told it will be, it 
may hereafter be the seat of his final home. 

4* And what is man ? For the purpose I have in 
view, it will be necessary to consider him in his very 
highest and in his very lowest relations, — on the one 
hand, as an organised being and in relation to this 
earth and the living creatures that inhabit it along 
with him, — and, on the other, as a spiritual being and 
in relation to the Creator and to the place or rank 
which he holds in the scale of being. 

5. Let us first of all consider him in his lowest re- 
lations. In relation to this Earth which he inhabits, 
man may properly be said to form a constituent part 
of it. He is literally taken from its very dust — of 
which indeed he is described as forming the highest 
part,* and when he dies he is resolved back into this 
dust again. So true is the quaint remark of Jeremy 
Taylor : " Our very graves were once living ; we dig 
through our forefathers, and must speedily become 
earth ourselves to bury our posterity." As an or- 
ganised being, he is constructed of the like materials, 
fashioned after the same general pattern, and subject 
to the same conditions of existence with the beasts 
that perish, and even with the corn that sustains him 
—in short, with the whole organised creation. And 
in' his merely animal relations, he is altogether so 

* Prov. viii. 26. 



192 



LETTERS ON TREES. 



allied to the higher orders of the lower animals, that 
all the phenomena of life as occurring in him may be 
illustrated by the corresponding phenomena as occur- 
ring in them.*^ Even in his instincts he partakes with 
them of a common nature. 

6. But man is somewhat more than this. The or- 
ganised body is merely the material tabernacle in 
which man dwells, and through the medium of which 
he has " a local habitation and a name/'' It is but 
the seat and the instrument of the immaterial prin- 
ciple which constitutes his proper self. And identical 
as it isj in structure and in function with the orc^anised 
bodies of the lower animals, there is yet that in it, 
different from theirs — its erect altitude and the pecu- 
liar conformation of the head and face and hands, which 
bespeaks for its occupant a higher nature than theirs. 

7. What, then, is man, viewed as an immaterial 
spirit ; and what his relations to his Maker, and what 
his rank in creation ? These are questions which it is 
more easy to ask than satisfactorily to resolve. JSTor 
do I see that without Revelation to guide us we can 
advance far in this inquiry. In times past, unassisted 
human reason did but grope in the dark, and arrived 
at no definite conclusion. Yet reason thus enhghtened 
may approximate towards a satisfactory solution of 
them. I say approximate, because we must bear in 
mind that much of the information given us in Scrip- 

* Alison. Outlines of Physiology ^ 3d ed. p. 9. 



LETTER XYIII. 



193 



ture on this subject is rather obscurely hinted at than 
directly stated ; and by a satisfactory solution, I mean 
such a solution as, when presented to her, though 
beyond her power to discover, reason can recognise 
as true— a solution which she can acquiesce in, as in 
harmony with what she has herself discovered of the 
Constitution and Course of Nature." 

8. So far, indeed, we may proceed in this inquiry 
without any guidance from Revelation. Natural reason 
can see that man is a spirit, endowed with understand- 
ing and conscience, with emotional susceptibilities and 
with voluntary power. And the commonest observa- 
tion is sufficient to demonstrate that he is the highest 
and the greatest of the living creatures that dwell on 
this earth. But it is from Revelation alone that we 
learn that he only, of all those creatures, has been 
made in the image and after the likeness of God ; and, 
vast as must ever be the distance between the creature 
and the Creator, that he has been made as high as a 
little lower than the Divine Nature * that he holds 

* Psalm viii. 5. — "A little lower than the angels." Milton has 
it — " Scarce to be less than Gods." Not to enter on an exegetical 
question which lies beyond my province, I would merely observe, 
on the authority of my friend the Rev. J. G. Wright, of St An- 
drew's Presbyterian Church, Southampton (to whom I am indebted 
for the view taken in the text), that in the original Hebrew, the 
word which our translators (herein foUov^dng the Septuagint ver- 
sion) have rendered " angels," is the same plural noun (Elohim) that 
occurs in the first verse of the first chapter of Genesis, and is there 

N 



194 



LETTERS ON TREES. 



to his Creator the relation of a " son," and by delega- 
tion from Him the rank of a " king ; " and that, as 
exercising kingly sway over the works of the Divine 
Hand, which have been put under his feet," he has 
been crowned Avith glory and honour." True : we 
see not yet all things put under him," neither do we 
see him yet thus crowned." But this, as Revelation 
assures us, is because man has fallen from his first 
estate. The kingdom that was appointed unto him, 
and which he held on condition of suit and service to 
be done, he forfeited by one fatal act of treason. The 
language of Scripture, therefore, is descriptive, not of 
what man is actually, but of what he was once, and 
might still have been. Rather is it descriptive of what 
man's condition is as restored. For it tells us that 
fallen man has been redeemed ; that by the interposi- 
tion of One who for him became man, and because of 
His exaltation to the throne of the universe, whereon 
he now sits as Man as well as God — man's Head and 
Elder brother — man has been taken back into his 
Royal Father's favour, all things have been again put 
under him, and his lost kingdom restored to him. 

9. Marvellous as it is, incredible but for the evi- 
dence on which it rests, such is, in truth, mian's rela- 
tion to the Creator, such his rank in the scale of 
creation : — the offspring of God, partaker of the 

rendered " God." " In the beginning God created," &;c.— See Note 
B, at the end. 



LETTER XVIII. 



195 



Divine Nature, of the ''blood royal of creation;"* 
invested with kingly dignity— crowned with glory 
and honour and immortality. 

10. Can we go further ? AVe may at least inquire 
whether man's position in creation be not '^unique;" 
whether, — excepting the angels which are but mini- 
stering spirits, and unto none of which hath God 
ever said Thou art my son," — man be not at once 
the only and the highest of created intelligences ? 
Whether this earth be not the only world that is 
inhabited by rational creatures ? Such is the view 
recently put forth by the author of the Essay Of 
the Plurality of Worlds^'' and argued by him with 
an ability which has at least excited the attention, 
if it has not commanded the assent, of the greatest 
of our philosophers. Such a view, I need scarcely 
say, would, if well-founded, lend the strongest con- 
ceivable support to the speculation which forms the 
proper subject of this letter. 

11. But we need not rest the speculation on so un- 
stable a footing as this. Revelation is silent on the 
question of a plurality of inhabited worlds, and phi- 
losophers are not agreed. Our whole race occupies 

but a spec in space, and as yet a spec in time.^f 
It may be, that there are other intelligences be- 
sides the race of man, and other worlds inhabited 

* Rev. R. C. Trench, B. D. Hulsean Lectures for 1846, Lec- 
ture iii. 

f Professor Powell. 



196 



LETTERS ON TREES. 



besides this — worlds older and larger and more glo- 
rious than ours, and intelhgences higher and purer 
and more noble than man — whose origin also may 
date from myriads of ages before his. Be it so. 
None can have been more highly favoured than he 
has been ; and there is surely warrant enough from 
Scripture, and from reason enlightened by Scripture, 
for the belief that there are no creatures in existence 
that are at once higher and different in kind from 
man, — however thev mav differ in the modes or the 
conditions of their existence. We may therefore re- 
gard man as being, at the least, the type and repre- 
sentative of the highest order of created being. And 
this -'more modest," and it may be, ''juster estimate 
of his place," will answer the purpose I have in view. 
If those other intelhgences be not clothed upon" as 
man is, their condition will not affect our specula- 
tion. If they be — if they have organised bodies 
and reproduce their kind, we may infer that in 
essential particulars, their constitution will be model- 
led after the pattern which has been followed in 
man's. 

12. Let us pause here for a little, and look at a 
principle which gives to the considerations now sub- 
mitted to you, all their force and value. It is the 
principle of ''unity of composition" — oi uniformity of 
plan as a ruling element in the constitution of the 
organic world. Of this principle I cannot give you a 
better idea than bv la vino; before vou a verv clear 



LETTER XVIII. 



197 



and forcible statement of it by Professor Powell. It 
is as follows : — 

*' Throughout all formations, the grand truth to which every 
accession of geological discovery bears witness in a more 
remarkable manner, is the principle of unity of plan continuall}^ 
exemplified in all the varieties of organic structures disclosed. 
Even the most seemingly monstrous and incongruous forms of 
animated existence in times past are all, without exception, 
constituted according to regular modifications of a common 
plan, and with parts, organs, and functions related by the 
closest analogies to each other; so that n) sooner is a new 
specimen detected than it immediately finds its proper posi- 
tion in the scheme of nature ; no sooner is a new form dis- 
covered than it is instantly assimilated with some known type, 
and found to hold an assignable place in the system. Whether 
a given organic fossil (as in some instances in more recent 
beds) exhibit characters difiering from some known form onl\^ 
as a variety or sub- species, or whether (as in earlier cases^ it 
present features unknown to any existing genus or order, or 
("as in other instances) offer conditions in any degree inter- 
mediate, still in all cases alike the remarkable point is always, 
that a place and a name can be immediately assigned to every 
new form as it presents itself ; and this too invariably in such 
a manner that it either tends to supply a link in affinity between 
orders of being already related, or indicates some new and 
unexpected point of analogy. There is never any deviation 
from system and regular plan ; we never light upon a fossil 
centaur or palaeozoic mermaid ; there never occui's any junction 
of heterogeneous members, any real departure from type and 
system. The invariahleness of the results through such enormous 
series of ages cannot but impress the mind, when duly considered, 
with the highest idea of the preservation of continuity ^ * 

* Essays. Ess. III. — On the Philosophy of Creation, ipi^. S37-S. 



198 



LETTERS ON TREES. 



13. Taking, then, the view we have done of man 
and of his relations, — having regard to his rank in 
the scale of being, and to the Hnks that bind him as 
well to his Creator as to this earth and the organic 
world therein, of which he forms a part, — viewing 
him also as at least representing the highest of created 
inteUigences, — and taking specially into account the 
manifest uniformity in his plans observed by the 
Creator, is it, let me ask, a vain imagination to sup- 
pose that, in the constitution of the lower forms of 
vegetable and animal life, which were made by Him 
thousands, nay, millions of years before man. He, to 
whom *^a thousand years are as one day," and who 

seeth the end from the beginning," should have 
had an eye to the constitution of him whom He so 
regarded, and has so highly exalted, and who, as an 
organised being himself, was one day to occupy the 
highest place in the organic world — and so have 
carried into their constitution a plan or scheme of 
organization befitting his, — befitting mind, — nay, not 
mind merely, for the brutes have this, but reason — 
that principle which, with its organ speech, has been 
denied to the brutes, which is in itself divine, and 
human only in that it has a place in man ? * 

14. The supposition seems to me both a reasonable 

* La raison est elle humaine, a parler rigour eusement, — ou 
bien n'est elle humaine que par eela seulement qu' elle fait son 
apparition dans Thomme ?" — Victor Cousin, Introduction a V 
Histoire de la PMlosophie. And as to speech being a divinely 



LETTER XVIII. 



199 



and a probable one. Let us apply it to the subject 
before us. 

15. As far as I can see, all plants might have been 
made to reproduce their kind from buds alone, certain 
of these being adherent/' as in the buds of trees, cer- 
tain others of them being free," like seeds, as in the 
Lilium bulbiferum, but not otherwise resembling seeds : 
and, as far as I can see, the same plan of reproduction 
might have been followed with the lower animals. It 
might have obtained also, for anything that appears, in 
the case of man. He might have been so constituted 
as of himself to fulfil his twofold mission of replenish- 
ing and subduing the earth. And, in point of fact, 
single and alone, man did at the first reproduce the 
species. In the history of our race, the bud in prin- 
ciple took precedence of the seed, introduced the 
seed, and having introduced it was withdrawn. Cain 
was the first-born of mankind, the joint offspring of 
Adam and Eve; but Eve was herself the prior off- 
spring of Adam. From a rib in his side, as from a 
bud, there sprang her who was the Mother of us all, — 
' Bone of his bone ; ' fair offspring of his side." * 

And nothing need have hindered the like mode of 
reproduction being continued. But the Creator judged 

imparted gift to man, and a standing evidence of divine interposi- 
tion in the world, see Archbishop Whately, in Introductory Lessons 
on the History of Religious Worship, Lesson I. 
* W. S. Oke, M. D., The Atonement, and other Poems, p. 4. 



200 



LETTERS ON TREES. 



another to be the better plan : — It is not good that 
the man should be alone. I will make him an help 
meet for him." An help meet for him ! One of his 
bone and flesh, one with him in heart and mind, but 
of a softer mould and a gentler spirit : one to share 
his mission with him, and, sharing it, at once to cheer 
and soothe and refine him ; to take upon herself, 
besides, the main burden of one part of that mission 
(leaving him the freer to fulfil the other), and in so 
doing, and exercising a mother's influence over their 
common offspring, to elevate the race of man ! 

16. Nor is this all. The gift to man of an help- 
mate is spoken of as if it had been an after-thought. 
The work of creation finished, God saw everything 
that he had made, and behold it was very good." 
Yet afterwards — after the Heir of Nature " had 
been put into the garden of Eden to dress it and to 
keep it," where he lived some time, longer perhaps 
than we are wont to imagine, single and alone, it is 
said — It is not good that the man should be alone." 
Not that there can be after-thought with the Creator ; 
not that the man was not at the first formed with a 
view to the gift he was afterwards to receive ; but as 
if to indicate that he might have been so organised as 
by himself, and without an helpmate, to replenish the 
earth as well as to subdue it ; and as if to indicate 
also that the principle of reproduction by seed in con- 
tradistinction to that by buds, had, as our view 



LETTER XVIII. 



201 



assumes, its real origin in man, its primary source in 
man's moral nature, and its true meaning in the insti- 
tution of marriage ; — an institution which, as it has 
been beautifully said by Bishop Taylor, " is the 
mother of the world and the nursery of heaven, liUing 
cities and churches and heaven itself — the proper 
scene of piety and patience, of the duty of parents 
and the charity of relatives — promotes the interests of 
mankind, and is that state of good things to which 
God has designed the present constitution of the 
world." * 

17. Hence a distinction of sexes, and hence a neces- 
sity for such a modification of the bud as we meet 
with in the seed. Hence also, peradventure, the real 
occasion of the seed. 

18. But if this whole view should be deemed too 
transcendental, I shall not insist upon it. Only grant 
me that the seed and the bud are co-ordinate and 
co-equal, different forms merely of one and the same 
thing, both answering the same end, but each in a 
way that the other cannot. Grant me this and I 
am content. You grant my whole theory of trees. 

19. And, now, not to pursue these speculations 
farther, but with the view merely of showing how 
truly identical in character and constitution both the 
bud and the seed are, let us glance for a moment at 
the skill and adaptation to circumstances, with which 

* Sermon On the Marriage Ring, passim. 



202 



LETTERS ON TREES. 



in two or three familiar instances in the vegetable 
world, sometimes the seed alone, and sometimes the 
bud and the seed together, are made use of. 

20. Take first the Cereals, includino^ Wheat, Rve, 
Oats, Barley, and others, — their relations to man 
and man's relations to them. In much that he should 
himself be capable of through his reason, man has 
been left to the resources of his reason and the labour 
of his hands. He has been so left, and that very ex- 
pressly, in the matter of his daily bread. The Cereals, 
accordingly, which supply this bread, and constitute 
in fact the staple article of his sustenance, bear seed 
only, are incapable of being propagated otherwise 
than by seed, and can be raised only in sufficient 
quantities for man's needs, by being sown by man's 
own hand, and in ground which his own hands have 
tilled. I have said in sufficient quantities, I should 
have said, can only thus be raised at all. For left 
to themselves, they disappear. Cultivated varieties 
as they all are, or rather abnormal conditions of some 
unknown species of Grass, they will not grow in the 
wild state. Ifot that when left to themselves they 
return (as do most cultivated varieties of plants) to 
their natural state and so become worthless, — but 
that they literally die out — wild plants, " thorns 
and thistles," and even the common grasses (their 
congeners) supplant them. Brought into their pre- 
sent state we know not when or how, they can be 



LETTER XYIII. 



203 



preserved for man's use only by careful husbandry. 
How strikingly does this accord with what we read of 
the curse passed on the ground for man's sake and 
the natural result of this — Thorns and thistles shall 
it yield thee and of the terms imposed on man in 
order to the procuring of his means of support — In 
the sweat of my face shalt thou eat bread," — terms 
no sooner imposed than man is " sent forth to till the 
ground." 

21. Consider next the " Grass of the field," which 
may be said to be the main-stay of the lower animals, 
and contrast it with the Cereals. Cursed for man's 
sake as the ground has been. Nature has yet made 
provision for those of her creatures that can neither 
sow nor reap." And thus, strictly annual as, accord- 
ing to my theory, all plants are, the common grass, 
producing buds as well as seeds, is by means of buds 
preserved in 2l permanent form on the earth's surface. 
Capable of being propagated by seed, largely propa- 
gated in this way from year to year by man himself, 
and thus chiefly in the first instance spread over the 
earth, sown broad-cast by Nature's own hand, it is also 
capable of being propagated by buds ; and from buds 
it now springs up annually, for the sustentation of 
animals, and that spontaneously, in far larger quan- 
tities than from seed. 

22. And to advert, as we appropriately may, to 
tree-plants, let us dwell for a little on some striking 



204 



LETTERS OlS TREES. 



points both of resemblance and contrast between them 
and the grasses. Slender and short-lived like them, 
annuals in fact as they are, they reproduce themselves 
also both by seeds and buds. And, as in the case of 
the grasses, the seeds of tree-plants serve to diffuse 
their species over the surface of the ground, while 
the buds cause sets of them to cluster together. 
Grass-plants and tree-plants differ only in this, that 
the former cluster together sideways, each plant strik- 
ing down directly into the soil, and so they come 
to cover the ground as with a carpet, while tree- 
plants cluster together in the vertical direction, and 
parasitically one set above another, and so they come 
at length to form masses which rise upwards — columns 
which point to the heavens above. 

23. Compare them next with the cereals, and con- 
sider the mutual relations of both to man. Created 
as expressly for man's use as the cereals have been, 
and remotely as essential to his existence as these are, 
tree-plants have yet been differently constituted in 
respect of the conditions of their existence. The 
cereals, as we have seen, cannot exist without man's 
toil and care. Tree-plants can and do exist indepen- 
dently of this. It might have been otherwise ordered, 
however. They might (hke the cereals) have been 
made dependent for their growth on him ; and man, 
as he can both sow and plant them, might have been 
left thus to provide himself with timber as he has been 



LETTER XVIII. 



205 



with bread. Nature, however, has been pleased not 
to lay this additional burden on him. Enough for 
her that he should toil and sweat for the supply of his 
daily recurring wants. She has herself anticipated 
and supplied his higher but more prospective wants in 
respect of timber. Nay, her supplies have ever been 
in advance and greatly in excess of man's numbers 
and man's wants, while they have been co-extensive 
with man's occupancy of all the habitable parts of 
the earth." 

24. Further still. Both by buds producing trees 
and by seeds multiplying their numbers, and likewise 
by apphances (such as geology is conversant with) as 
well for preserving from decay the timber thus pro- 
duced as for changing its physical qualities, provi- 
sion has been made quite independently of man, and 
long before man's appearance on the earth, for the 
production of CoaL The manifold uses of this sub- 
stance lie beyond my province, as do those of timber. 
But I beg you will bear in mind that since trees, as 
such, come and can come only of the biid^ so to the 
bud is man beholden for the advantages which both 
timber and coal have given him. So important in the 
economy of Nature is the Bud ! — 1 am, &c. 



LETTER XIX. 



" All knowledge is to be referred to use and action." 

Lord Bacon. 

" Be aye stickin' in a tree, Jock ; it'll growe whaun ye're sleepin'." 

Sir Walter Scott, Bart. 

September 20, 1855. 

My Dear Sons, 

1. If my theorj^ be a sound one, it should be worth 
something. It should supply a reasonable answer to 
the question — Cui bono ? 

2. One use it will clearly serve — that of explaining 
various phenomena occurring in trees, and that of 
solving sundry questions presenting themselves in con- 
nection with trees — such questions as those relating 
to their age and size, the very variable duration of 
trees of the same species or of different species — and 
such phenomena as the unequal growth of trees on 
different sides, the winding course, or the strange 
bundling and plaiting of the woody fibres in the trunk 
of some trees, the vigorous state of many trees, even 
after the trunk is in a state of decay and quite hollow, 
the existence of roots in the chasms, and of birds' 



LETTER XIX. 



207 



nests, frogs, stones, and such-like in the very heart 
of trees, enclosed and completely buried in sound 
wood. It will also have a rehgious and moral use, as 
I shall endeavour to show you in my next letter. 

3. But the use and application of the theory which 
I have in view at present is a material one — such as 
the gardener may turn to account in the management 
of his fruit-trees, the farmer in that of his orchards, 
and, above all, the forester in that of his plantations, 
and of the park or ornamental timber. I have no 
doubt, indeed (assuming it now, as I think we may, to 
be a true theory), that it may be useful in that way ; 
and I have in my mind one or two uses which it seems 
to me it may serve. But 1 beg to observe, in the first 
place, that having myself had no practical experience 
in matters of this kind — having lived all my days in 
towns (which Cowper says " man made," and in the 
making of which he ruthlessly lays the axe to the root 
of the aboriginal occupants of the ground), and not in 
the country (which the same authority says God 
made," and where these find their proper field, and 
receive fitting treatment) — you will not expect that I 
should be so ready in the practical as in the theoretical 
department of my subject ; and, in the second place, 
that it is no fair test of the merits of a theory that the 
proposer of it should be able to point out the applica- 
tions of it. Galvanism was for a very long time little 
else than a barren theorv, and Galvani, who first 



208 



LETTERS ON THEES. 



brought it to light, had no idea of the use that has 
within your own recollection been made of itj in 
the all but instantaneous interchange of thought be- 
tween persons living many thousand miles apart, or 
that will yet be made of it when the electric telegraph 
overspreads the globe. The discovery of the laws of 
latent caloric did not at once lead to the application of 
steam as a moving power. 

4. In thus referring, therefore, to the uses of the 
theory, it is not in the hope or expectation of turning 
it to practical account myself, but rather with the 
view of showing you that I neither overlook Lord 
Bacon's maxim, nor feel mdifferent as to the way in 
which the Author of Waverley's friend Jbcfc" may 
best carry out the advice given him, and so make two 
trees grow where only one grew before. 

5. All that at present occurs to me on the subject 
may be comprised in one or two observations, which, 
moreover, I desire to submit less in the way of confi- 
dent assertion than of " guesses at truth." 

6. And, first, it seems clear from the view taken of 
the relation to the woody tissue, of the plants emana- 
ting from the buds, that, as the quantity of that tissue 
is always proportioned to the number of the plants, 
so caution should be exercised in the pruning of 
trees, — and precaution taken so to plant them in the 
first instance, and so to weed them afterwards, as to 
give the side plants air and room to grow, as they 



LETTER XIX. 



209 



naturally will, if allowed — taking due care where 
necessary, in conducting the latter operation (while 
not deferring it too long), not to withdraw, by over- 
thinning, the support and shelter which the trees 
give to one another. All this, indeed, the practical 
forester knows very well, and habitually acts upon ; 
but I think my theory explains the reason better 
than the old. 

7. Secondly, The fact of the tree-plants of one year 
being essentially independent of those of the past and 
the next, and of each year's crop of timber essentially 
standing by itself - — varying in quality, no doubt, as 
in quantity, as is the case with the cereals and their 
produce, — may perhaps furnish a good ground of 
hope to the land-owner that a disease affecting his 
plantations this year — and even for a series of succes- 
sive years — may be purely temporary^ and not in the 
end blight his prospects in respect of them. JiTo 
doubt, even on the supposition that every tree is 

one integer," or an individual plant, that hope may 
be entertained. Disease, as a general fact, is in its 
own nature temporary, and on this ground alone a 
diseased plantation might be expected in the course of 
time — either spontaneously or by the aid of suitable 
appliances (among which efficient drainage* seems to 

* " Since I came to Arniston as forester, I have recovered a 
considerable extent of young larch plantations, which were fast 
going back, and that simply by draining the soil, in order to draw 

O 



210 



LETTERS ON TREES. 



be the most important) — to recover itself. And this 
we know very well has happened. Some years ago, 
in many parts of the kingdom, in Scotland particularly, 
the larch plantations " went wrong." Several were 
almost destroyed by the disease that affected them ; 
others, however, recovered, and ^re now to all ap- 
pearance in as sound a state as ever. Still, I think 
my theory affords a better ground of hope in that 
respect than the old, — and that just to the extent 
and in the way that we may in general reasonably 
expect, that a child will escape a disease — incurable it 
may be — -under which one or other, or even both of 
his parents labour, — or, if himself inheriting and 
participating in it, will not impart it to his own off- 
spring ; in other words, that a morbid taint attaching 
to one or two in the immediate succession will not 
in all probability be transmitted from generation to 

away from it superfluous water, as well as to cleanse it from bad 
qualities wiiich were natural to it, and formerly prevented the 
healthy development of the larch tree. These young larch planta- 
tions were under fifteen years of age when I drained them; but I 
cannot say if draining would recover plantations of older standing. 
In all cases where it is desirable to cultivate sound larch timber, 
the land should be drained with, open cuts at from thu'ty to fifty 
feet distance, according to the nature of the soil, and not shallower 
at first than eighteen inches deep ; and as the plantation advances 
in age, the di-ains should be gradually deepened, and kept properly 
clean; for however well land may be drained at first, if those drains 
are not kept in a clean running state, they will ultimately be of very 
little benefit to the rearing of healthy larch."—" The Forester,'" <SfC. 
by James Brown, forester, Arniston, 2d Ed. pp. 412-13. 



LETTER XIX. 



211 



generation indefinitely, and so be perpetuated in the 
family. 

8. And this observation we may, I think, apply to 
the Potato and its disease," and likewise to the 
Vine, the Hop, the Peach, and their diseases." 
Heretofore, the diseases which have so widely pre- 
vailed — in fact epidemically — among the plants in 
question, and which have proved so destructive to 
them and so disastrous in their issues to the people 
of many countries, have eluded all attempts to ascer- 
tain either their real nature or their exciting causes, 
as well as baffled the skill of man either to prevent or 
cure them. And our main hope, it appears to me, 
must lie in the evanescent character of the diseases 
themselves and the restriction of them to individual 
generations only, of the race to which the plants re- 
spectively belong, 

9. One qualifying observation I must needs add in 
regard to trees, which is, that it may be a question, 
even in the point of view just adverted to, whether 
the timber produced by diseased plants, overlying, on 
the one side, and overlaid by, on the other, the sound 
timber of pre-existing and succeeding healthy plants, 
may not affect the quality of the entire " Timber- 
stack." — May not the seeds of the ^'dry-rot" in 
timber, for example, attach themselves primarily to 
particular rings or cylinders of the tree, and have 
their origin, not so much — or at least so exclusively, 



212 LETTERS ON TREES. 

as some have fancied, in the felHng of the tree at a 
time when it is full of sap, — as in the ill-developed 
and ill-conditioned woody-tissue, the produce of the 
diseased plants of a particular year or series of years? 
Such tissue, it is conceivable, may be as perishable in 
its degree and as prone to decay as the diseased potato- 
tuber, but the tendency thereto be prevented, as long 
as the tree is in the ground and growing, by the more 
complete exclusion of the tissue from external agencies 
than does or can obtain in the case of the latter — an 
exclusion becoming every year still more complete 
and perfect by the deposition of new woody-tissue 
around it, breaking forth, however, after the tree has 
been felled, sawn up, and exposed to air and mois- 
ture — to the latter especially. It would, I think, be 
worth while to examine microscopically and otherwise, 
the timber of trees which are known at a certain 
period of their growth to have been diseased, and to 
compare the woody tissue of the cylinders of the 
several years. There are marked organic differences, 
easily detected by the microscope, and sensible chemi- 
cal peculiarities elicited by analysis, between the tubers 
of healthy and diseased potatoes. And like or equally 
notable differences may exist in the woody tissue of 
diseased and healthy tree-plants. — I am, &c. 



LETTER XX. 



" He hath given them a Law which shall not be broken." 

Psalm cxlviii. 6. 

The Laws of Nature are the Thoughts of Nature ; and these 
are the Thoughts of God." CErsted. 

" And this our life, exempt from public haunt, 
Finds Tongues in Trees." 

As YOU Like it. 



November 29, 1855. 

My Dear Sons, 

1. I hope we may now consider ourselves fairly 
'^out of the wood," and, standing where we do, en- 
titled to congratulate ourselves that, in wending our 
way through it, we have neither stuck fast in the 
mire, nor been driven by a lion in our path" into a 
course other than that we intended to pursue. Setting 
out as we did in the dim twilight, with a mere hypo- 
thesis for our guide, I would fain persuade myself 
that we have at length reached the stable platform 
of a sound theory ; and that in the broad day and 
clear sunshine which now surrounds us, we can plainly 



214 



LETTERS ON TREES. 



perceive in the facts that have passed under our view, 
one common principle running through and connecting 
them all, one general fact embracing and expressive 
of them all. 

2. If so, I would wish to lead you one short step 
farther. If my theory be a sound one, it is the 
expression of a Law of Nature ; if our inquiries have 
brought us within the view of a general fact or common 
principle, including and explaining a number of indi- 
vidual, and, in themselves, solitary phenomena, they 
have brought us within the view and to the grasp of a 
Law of Nature. 

3. But what is a Law of Nature ? To say that it 
is the expression of an ultimate fact in nature, of which 
no other account can be given than that it depends on 
the will of the Author of Nature to say that " Laws 
of Nature are nothing else but the most general facts 
relating to the operations of Nature, which include a 
great many particular facts under them,"f is, it seems 
to me, a definition which convevs but half the truth — 
nay, which by its negative form obscures it altogether. 
We may, I think, rise a step higher than this, and, 
defining it positively, say with Plato, that a Law of 
Nature is the expression of an idea in the divine 
mind — the manifestation of a plan or purpose in the 
mind of the Creator. To discover a Law of Nature is 

* Alison, Outlines of Physiology, 3d Ed. p. 8. 

t Reid's Inquiry into the Human Mind, chap. vi. § 13. 



LETTER XX. 



215 



to get within the veil behind which the Creator works 
in secret. It is to come into contact with His mind, 
and see Him thinking and planning and ordering as 
seemeth unto Him good, in regard to that which forms 
the subject of the law.* 

4. The happiest expression of this view is that 
given by QErsted : The Laws of Nature are the 
thoughts of Nature, and these are the thoughts of 
GodJ' That, 1 apprehend, is the proper notion of a 
Law of Nature. The term law, it seems to me, bears 
or should bear tiie same import in natural science that 
it does in ordinary jurisprudence. A law of this realm 
of England is an expression of the mind and will of 
the people of England, as declared through the legis- 
lature; and when doubt or difficulty arises in the 
interpretation of it, reference is continually made to 
the known or supposed design of the legislature in 
the enacting of it. To say of the laws which regulate 
the succession to property that they are statutes, of 
which no other account can be given than that they 
form part and parcel of the laws of the land, and 
depend on the will of the legislature, would probably 
be regarded as not altogether a satisfactory account 
of them by a student of English history, intent on 
getting at the root or principle, and mastering the 

* See, for a fuller elucidation of this view, Dialogues on Natural 
and Revealed Religion, by the late Rev. Robert Morehead, D.D. 
(1830) — Preliminary Inquiry, 



216 



LETTERS ON TREES. 



philosophy of our constitutional forms, and of our 
national traditions and social usages. 

5. And this notion of law is distinct from that of 
power. Power, indeed, is itself regulated by law — 
i. e. by design or purpose, and is therefore expressive 
of mind — into whichj in fact, all power as well as all 
law is resolvable. But still law is not power. The 
two are as distinct in the economy of Nature as they 
are in the economy of human affairs — as distinct in 
Nature as a law of this realm is distinct from the exe- 
cutive power of the realm by which it is enforced. 
The time-tables of a railway company set forth the 
law — ^. e. the purpose of the company, in the person 
of the directors, in regard to the departure and arrival 
of the several trains at the different stations along the 
line. And the trains do in fact arrive and depart in 
obedience to that law. But the law in question is not 
the power by which the movement of the trains is 
effected ; nor does it give us any insight into the 
nature of that power. So, also, the phenomena of 
Nature take place in accordance with (or in obedience 
to) the laws of Nature, and these laws are expressive 
of ideas in the Creator's mind — embodiments of His 
thoughts and purposes. But they are not the powers 
employed by Nature in the production of the pheno- 
mena, nor do they lead us one step towards the know- 
ledge of them. The Creator has let us into many of 
the secrets of His counsel ; but He has carefully hid 



LETTER XX. 



217 



from us most of the secrets of His power, lest we 
should ourselves become as Gods, and work like Him. 
In the hands of Cuvier, a single fossil-bone, the only 
remains he had of an extinct animal, disclosed to that 
physiologist the entire animal — its structure and func- 
tions, its instincts and habits, the object of its existence 
— the whole purpose (one may say) of the Creator 
regarding it — a disclosure afterwards verified by the 
discovery of the complete remains of another specimen 
of the same anim.al. But it did not and could not dis- 
close to him the power by which it was made, and by 
the knowledge of which he might himself make and 
put life into such an animal. In like manner, the fall- 
ing of an apple (at least so the story goes) led Newton 
to the discovery of the great law of gravitation, in 
obedience to which the movements of the heavenly 
bodies take place. But it taught him nothing as to the 
efficient power of gravitation itself. The key which 
laid open to Newton and Cuvier the repository of 
laws — of plans, patterns, and specifications — was not 
the key that answer to the stronger lock which bars 
the tool-house and the work-shop of Nature. 

6. What now is the law written upon trees ? What 
the language which they speak ? This : That though 
constructed to last for ages and generations, and to 
grow to an enormous size — without set limit to their 
asfe or size, they are vet fashioned after the same 
model with other plants — modified only with express 
reference and in manifest adaptation to a special end. 



218 



LETTERS ON TREES. 



7. Do you ask what the general plan or idea is ? 
The answer is, that short-hved, small, and slender 
annuals are the basis of the whole yegetable creation, 
the principle on which the whole is contrived, the 
true types and proper representatives of all plants. — 
" Trees come of us, not we of trees." So, as we tread 
it under foot, gazing at some majestic and venerable 
Oak — so might the little Daisy say, addressing us in 
the name and on the behalf of its fellow annuals. 

Giant as that proud Oak is, reaching back though 
he may to ages earlier than the Conquest, he yet con- 
tains no element that is not to be found in us. The 
Grass of the field which in the morning groweth up 
and in the evening — its growth completed — is cut 
down and withereth, cometh of an older line than 
his."* 

8. And do you ask next what the special end is, to 
meet which the general plan has been modified in the 
case of trees ? It is mainly the production of Timber, 
And what the modification itself? Let us again 

* " Kings come of us, not we of kings. — Nos no descendemos de 
ios Reyes, sino los Reyes descendien de nos,". — is said to be the 
device of the Manriquez family. — " I think. Sir Edward, that you 
are of the family of the Duke of Somerset." " Pardon me. Sir, the 
Duke of Somerset is of my family." Reply of Sir Edwand Sey- 
mour, the head of the elder branch of the Seymoui's, to William, 
Prince of Orange, who, at his first interview with Sir Edward, 
meaning to be very civil to him, had addressed him as above. — See 
Macaulay's History of England, vol. ii. 



LETTER XX. 



219 



examine this a little in detail. It is so simple as 
almost to elude observation, yet, as soon as seen, so 
manifestly a scheme or contrivance — so like in kind 
to what we ourselves might any one of us have devised, 
that we cannot help identifying it with mind; and 
withal so in keeping with the general idea, that we 
cannot but regard both the idea and the scheme as 
the offspring of one and the self-same mind. The 
modification lies chiefly in this, — in the property 
bestowed on the tree-plant of growing parasitically on 
the root of its dead parent, and of so growing on this 
root as to cover it over, enclosing it on every side and 
throughout its length. It lies partly also in this, — 
that the root itself is made somewhat firmer, and 
therefore less quickly perishable than the root of the 
ordinary annual. I say somewhat, because it need be 
(and is in fact) only sufficiently firm to last till the 
following season, that it may then serve as the support 
or axis for the new plant of that season to rest and 
grow upon. This purpose served, the root in ques- 
tion is henceforth cut off, in the way just adverted 
to, from the destructive agency which external in- 
fluences tend uniformly to exert on all dead organic 
matter. It is sheathed over, hermetically encased, 
and thus (though naturally very perishable), effec- 
tually protected against the joint and otherwise 
irresistable action of air and heat and moisture. 

9. Physiologically, this modification of the general 



220 



LETTERS ON TREES. 



plan is unimportant. The peculiarities which attach 
to the tribe of tree-plants are in that respect insigni- 
ficant. Yet in their manifest intention and their actual 
result they are all important. For they plainly 
bespeak a plan or purpose in the mind of the Creator. 
Provisions thev are of His, wherebv out of short and 
slender annuals. He forms timber for the use of man, 
— and whereby in the ages that are past He formed 
coal also for the service of man — substances both of 
them which minister in a thousand different ways to 
the comfort and the well-being of man's race, but the 
production of which would have been impossible had 
not the economy of the plants in question thus dif- 
fered from that of all other annuals. 

10. Nor this alone. Those very peculiarities point- 
ing, as they do, to a common plan as the basis on which 
tree-plants have been constructed, indirectly but all 
the more strikingly evince the essential unity of the 
plan in conformity to which all plants haA^e been con- 
structed. The whole vegetable kingdom, therefore, — 
the extremes of it thus meeting — is expressive of the 
same idea, and bears witness that it is the conception 
of one Divine mind, the handiwork of the same 
Almighty Power. 

11. Thus and so unmistakably do Trees seem to me 
to testify of the Creator. or is this all that they tell 
us. Their language is rich and copious. It is expres- 
sive also as well of emotions as of ideas — of joy and 



LETTER XX. 



221 



gladness, of sadness and sorrow, of awe and gratitude, 
as of truth and beauty, of power and might and 
majesty, of wisdom and goodness. To understand 
their language, however, in all its fulness and variety, 
and to hold famihar converse with them, is what few 
are equal to. It requires perceptive and suggestive 
faculties of a particular order, and peculiar emotional 
susceptibilities. Yet even we, as we stand beneath 
their shade or walk among them, though wanting in 
those gifts, may yet catch enough to make us wiser 
and better. The wind sweeping through them, and 
" made vocal " in their service, may perchance waft 
to us their morning or their evening hymn — their 
own Jubilate Deo : — 

O be joyful in the Lord : Trees of the wood that rejoice 
before Him ; 

It is He that hath made us ; and not we ourselves — 
Monuments of His mind and hand, emblems of His years, 
and channels of His love to man." — 

And the while, from the green sward on which we 
tread, we may hear still another voice coming to us in 
accents at once " gentle and unreproving," and saying 
to us individually — Take thy shoes from off thy 
feet, for the place whereon thou standest is holy 
ground." Let our response be — " Surely the Lord is 
in this place, and I knew it not. This is none other 
than the house of God, and this the gate of Heaven." 
And lifting our eyes upward in this Temple of 



222 



LETTERS ON TREES. 



the Living God," and therein " seeing Him who is 
Invisible/' let us with subdued yet cheerful hearts, 
whisper to ourselves, each one to himself, I have 
heard of Thee by the hearing of the ear, but now 
mine eye seeth Thee !" — I am, &c. 



POSTSCRIPT. 



In Letter IX., section 21 (page 90), I speak of our 
having annually a crop of timber^ just as we have 
annually a crop of corn. I might have added that 
the former has equally with the latter, a moyiey value, 
which, though it cannot be so quickly realised or so 
accurately computed, as in the case of corn, may yet 
be approximatively estimated and shown to form an 
important item in the yearly rental, and the accruing 
value, of an estate on which extensive plantations 
exist. On this subject details of great interest are 
given by my friend and relative, Robert vSmith, Esq., 
of Glenmillan, in a paper entitled Report of Plant- 
ing on the Estate of Balgowan,'' in Aberdeenshire, — 
for which Report the Highland and Agricultural 
Society of Scotland (to which it was presented) re- 



224 



LETTERS ON TREES* 



cently awarded him a Gold Medal* By permission, 
I am enabled to append certain details to these 
Letters. They relate exclusively to two kinds of 
timber — Larch and Scotch Fir — and are comprised 
under the head of General Observations.'' They 
are as follows : — 

" For the first twenty- five years, it may be prudent to 
assume, that, in a purely agricultural district, where there is 
not a scarcity of wood, no return whatever will be derived from 
a Larch and Scots Fir plantation, — any price obtained for 
thinnings being exhausted, if not more than exhausted, in the 
expense of cutting. In ordinary cases, after the lapse of 
twenty-five years, — or, say, thirty years at the most, — the 
thinnings become fit for fencing, coal- props, &c. ; and if the 
plantation be a thriving one, and the locality within an average 
distance of conveyance by water or rail — suppose five miles,— the 
returns become considerable. It were a very moderate estimate 
to assume, that, for the period of the plantation's age, between 
thirty and forty, a free annual return of 10s. per acre may be 
obtained. At the end of forty years, we may assume that 450 
trees per acre will remain — say one half Larch and one half 
Scots Firs.f If still in a thriving condition, few will be sold 
for some years ; they are too old for coal- props and fencing, 
and, generally, too young for fiooring, railway- sleepers, &c. 

* This report will appear in the ^' Transactions " of the Society — 
to be published in January 1856. 

f The plantation to which Mr Smith's report relates, was laid 
down (in 1851) in the proportion, per acre, of 2400 two-year-old 
seedling Scots Firs, and 600 two-year-old seedling Larches — and in 
such manner that the subsequent thinnings should be chiefly confined 
to the Scots Firs. 



POSTSCRIPT, 



225 



They are now in a state when their annual increase in growth 
and value is very great. At the end of sixty years, the inter- 
vening period from forty has probably disposed of 150 trees 
per acre, at an average price, we shall assume, of only one 
shilling per tree — after deducting expenses and allowing for 
dead trees — giving L.7, 10s. per acre. We have now 300 
trees remaining for each acre, and shall suppose that they 
consist of Larches and Scots Firs equally. Of course, there 
wiU be considerable variety in the size, but, assuming that 
each acre contains 

Fifty Larches, worth on an average only 5s. 

each, L.12 10 0 

And fifty Scots Firs, worth 2s. 6d., . . 6 5 0 

With the remaining two hundred trees, at say 

on an average of only Is. 6d., . . 15 0 0 



We have a total value per acre of . L.33 15 0 



The result of the foregoing estimate would stand thus : — 
Original expense of planting and enclosing, 

L.l, 4s. 9d. per acre, or say . . . L.l 5 0 
Compound interest at 5 per cent for thirty years, 
the thinnings to that date being held as an 
equivalent for the expense of cutting, &c.. 5 8 0 

Total per acre, . . . L.6 13 0 



For the period of the wood's age, between thirty and 
forty, we held the thinnings as worth 10s. per annum, per 
acre ; but as the Reporter would rather have his estimate 
below than above the truth, we shall place the return for this 
period simply as equal to the current interest then accruing. 

P 



226 



LETTERS ON TREES. 



For the period of growth, from forty to sixty, we have esti- 
mated the return at only L.7, 10s. per acre, that being a time 
w^hen it is desirable to cut as few trees from a thriving w^ood 
as possible — 



Or, per acre, per annum, , 


L.O 


7 


6 


Less interest on L.6, 13s., amount of expense, 








and coniDOund interest thpreou as hpforp 


0 


6 


8 


Leaving per acre, per annum. 


L.O 


0 


10 


And giving for twenty years, per acre. 


L.O 


16 


8 


xne price at ine enci oi sixi^ j eaib w as esiimaieu. 








as before, per acre, at . 


33 


15 


0 


Making a total of . . . 


L.34 


11 


8 


From w^hich deduct original outlay and compound 








interest, . . . . . 


6 


13 


0 


Free balance per acre, 


L.27 


18 


8 











Or, taking the full amount for a plantation of the extent 
of that reported on (190 acres), we have — 
Original cost and compound interest, as before, 

one hundred and ninety at L.6, 13s., L.1263 10 0 

Price, ditto, at L.34, lis. 8d., . . 6570 16 8 



Balance or gain, . L.5307 6 8 



This return is equal to a rent at the rate of 9s. 3d. per 
acre, per annum for sixty years, for ground literally worth 
nothing before, besides leaving a surface of decayed vegetable 
matter, growing pasture-grass in place of heath, and having 
all along afforded shelter and beauty to the adjoining gTounds. 



POSTSCRIPT. 



227 



" By some the preceding estimate will be thought too high, by 
many too low. The Reporter admits that the value to which a 
young plantation will arrive cannot be predicated with certainty. 
There is an infinite variety of causes that may supervene to 
atfect it — soil, seasons, state of markets, &c. He can point to 
a plantation, chiefly of Larches, on the Estate of Finzean, on 
Deeside, about fifty years of age, already w^orth about L.80 
per acre ; and, in other parts of the country, to plantations of 
almost equal age, not worth much more than L.5 per acre. 
But in any view, if the expense of planting be not above an 
average, and if the soil be not wholly unsuited for it, it is a 
good investment. The returns by way of shelter, amelioration 
of climate, increase of pasture-grass, and ready wood for 
smaller country purposes, if not for extensive sales, afford an 
ample remuneration for the original cost." 



THE END. 



APPENDIX. 



l^OTES 



Note A. — Letter XIY., page 154. 

Dr Lindley thus expresses himself in regard to the excep- 
tions taken to the doctrine of the woody tissue of trees being 
descending matter : — 

The most important of the objections which have been 
taken to this opinion are the following : — If wood were really 
organised matter emanating from the leaves, it must neces- 
sarily happen that in grafted plants the stock would in time 
acquire the nature of the scion, because its wood would be 
formed entkely by the addition of new matter, said to be fur- 
nished by the leaves of the scion. So far is this, however, 
from being the fact, that it is well known that, in the oldest 
grafted trees, there is no action whatever exercised by the 
scion upon the stock ; but that, on the contrary, a distinct line 
of organic demarcation separates the wood of one from the 
other, and the shoots emitted from the stock, by wood said to 
have been generated by the leaves of the scion, are in all 
respects of the nature of the stock. Again, if a ring of bark 
from a red- wooded tree is made to grow in the room of a 
similar ring of bark of a white-wooded tree, as it easily may be 



232 



LETTERS ON TREES. 



made, the trunk will increase in diameter, but all the wood 
beneath the ring of red bark will be red, although it must have 
originated in the leaves of the tree which produces white wood. 
It is further urged, that, in grafted plants, the scion often over- 
grows the stock, increasing much the more rapidly in diameter ; 
or that the reverse takes place, as when Pavia lutea is grafted 
upon the common horsechestnut ; and that these circumstances 
are inconsistent with the supposition that wood is organic 
matter engendered by leaves. To these statements there is 
nothing to object as mere facts, for they are true ; but they 
certainly do not warrant the conclusions which have been 
drawn from them. One most important point is overlooked 
by those who employ stich argimients, namely, that in all 
plants there are two distinct simultaneous systems of growth, 
the cellular and the fibro- vascular, of which the former is 
horizontal, and the latter vertical. The cellular gives origin to 
the pith, the medullary rays, and the principal part of the cor- 
tical integument ; the fibro-vascular to the wood and a portion 
of the bark : so that the axis of a plant may be not inaptly 
compared to a piece of linen, the cellular system being the 
woof, the fibro-vascular the warp. It has also been shewn by 
Knight and De Candolle that buds are exclusively generated 
by the cellular system, while roots are evolved by the fibro- 
vascular. Now, if these facts are rightly considered, they will 
be found to ofi'er an obvious explanation of the phenomena 
appealed to by those botanists who think that wood cannot be 
matter generated in an organic state by the leaves. The 
character of wood is chiefly owing to the colour, quantity, size, 
and distortions of the medullary rays which belong to the 
horizontal system : it is for this reason that there is so distinct 
a line drawn between the wood of the gi'aft and stock ; for the 
horizontal systems of each are constantly pressing together 
with nearly equal force, and uniting as the tmnk increases in 
diameter. As buds from which new branches elongate are 



NOTES. 



233 



generated by cellular tissue, they also belong to the horizontal 
system ; and hence it is that the stock will always produce 
branches like itself, notwithstanding the long superposition of 
new wood which has been taking place in it from the scion. 

" The case of a ring of red bark always forming red wood 
beneath it, is precisely of the same nature. After the neyv 
bark has adhered to the mouths of the medullary rays of the 
stock, and so identified itself with the horizontal system, it is 
gradually pushed outwards by the descent of woody matter 
from above through it ; but, in giving way, it is constantly 
generating red matter from its horizontal system, through which 
the wood descends, and thus acquires a colour not properly 
belonging to it. With regard to the instances of grafts over- 
growing their stocks, or vice versd^ it seems that these are sus- 
ceptible of explanation on the same principle. If the horizontal 
system of both stock and scion has an equal power of lateral 
extension, the diameter of each will remain the same ; but, if 
one grows more rapidly than the other, the diameter will 
necessarily be different : where the scion has a horizontal 
system that developes more rapidly than that of the stock, the 
latter will be the smaller, and vice versa. It is, however, to be 
observed, that in these cases plants are in a morbid state, and 
will not live for any considerable time. 

Another case was, that if a large ring of bark be taken from 
the trunk of a vigorous elm or other tree, without being 
replaced with anything, new beds of wood will be found in the 
lower as well as the upper part of the trunk ; while no ligneous 
production will appear on the ring of wood left exposed by the 
removal of the bark. ISTow this is so directly at variance with 
the observations of others, that it is impossible to receive it as 
an objection until its truth shall have been demonstrated. It 
is well known, that, if the least continuous portion of liber be 
left upon the surface of a wound of this kind, that portion is 
alone sufficient to establish the communication between the 



234 



LETTEES ON TREES. 



upper and the lower lips of the wound ; but, without some 
such slight channel of union, it is contrary to experience that 
the part of a trunk below an annual incision should increase by 
the addition of new layers of wood until the lips of the wound 
are united, unless buds exist upon the trunk below the ring. 
The horizontal parenchymatous system may, however, go on 
growing, and so form new layers. 

Dutrochet mentions some cases of extraordinary longevity 
in the stock of Pinus Picea^ after the trunk had been felled, 
and which he supposes fatal to the theory of wood being formed 
by the descent of organised matter. He says that, in the year 
1836, a stock of Pinus Picea, felled in 1821, was still alive, 
and had formed fourteen thin new layers of wood — that is, one 
layer each year ; and another, felled in 1743, was still in full 
vegetation, having formed ninety-two thin layers of wood, or 
one each year. But, it is now ascertained that these roots are 
connected with living stems in consequence of having become 
grafted, under ground, to the roots of the latter. 

''The observations of Mirbel on the origin of the woody 
bundles of Palm-trees, from which it appears that the bundles 
first appear isolated in the cellular matter of the buds, and 
then direct themselves upwards into the leaves and downwards 
into the trunk, are certainly opposed to the possibility of 
regarding wood as the roots of leaves. And the difficulty of 
admitting the theory is much increased by the existence in 
bark of the embryo buds, already described; and by M. 
Decaisne's statement, that in the Beet-root, when new vascu- 
lar tissue is produced, it, in the beginning, is distinct from the 
previously formed vascular tissue. 

'' The singular examples of carved figures being found in the 
interior of trees also militate somewhat against the theory of 
wood being a form of roots, and are better explicable upon the 
supposition of a gradual superficial deposit. A very curious 
example of this is to be found in the Gardener's Chronicle for 



NOTES. 



235 



1841 (p. 828) ; others have been occasionally met with ; and 
Link has figured one in his Icones Selectee (Part ii., t. 2, fig. 7), 
which he speaks of thus : — ' I found such letters in a Lime- 
tree near Berlin, on an estate belonging to the deceased mini- 
ster, Count Yon Luttum ; the letters on the one side of the 
split piece were hollow, on the other elevated, and the cavity- 
had evidently been filled up again with a woody substance. 
This fiUing-up substance, on making a transverse incision, 
exhibited rather irregular layers, with a moderate magnifying 
power. And on being magnified 315 diameters, it evidently 
consisted of strata of larger and smaller cells, partly filled up, 
partly empty, with interstices. The circumstance, however, 
which appears particularly remarkable, is, that the internal 
structure of the fiUing-up substance, on a longitudinal incision, 
corresponded very nearly vfith the old wood situated next to 
it, with the difi'erence only, that spiroids existed in the latter, 
which were entirely absent in the new wood. It will be seen, 
therefore, that the formation of layers is peculiar to the wood, 
and is by no means caused by external influences.' " — Intro- 
duction to Botany, vol. ii. Pp. 197-201. 

This whole extract bears on one particular view of the 
woody tissue and its mode of evolution — that which regards it, 
exclusively, as descending matter^'''' and evolved by the actual 
descent of this matter /rom the leaves. The greater number of 
the objections to this view seem to be satisfactorily met and 
answered by Dr Lindley. There are other objections, how- 
ever, not so easily disposed of, regarded seemingly by Dr 
Lindley as real, and pointing to a superficial deposit in situ., 
from the Cambium, as the actual mode of its evolution. It 
appears to me that the view taken in the text, which recognises 
both modes of evolution — an evolution in situ as well as an 
evolution hy descent — not merely solves all the difficulties, but 
is required to explain all the phenomena connected with the 
formation of the woody tissue. 



236 



LETTERS ON TREES. 



Note B— Letter XYIII., page 193. 

With regard to the exegetical question referred to in tlie 
foot-note, one or two additional remarks may be made here. 
And first, the late Professor Lee of Cambridge, in his Lexicon^ 
under the head of the Hebrew word EloMm^ observes " It 
has been supposed occasionally to signify Angels^ but there is 
no real necessity for this," — adding, in a foot-note, that — 
" The Jewish commentators and translators of the Scriptures, 
as well as their Samaritan neighbours, filled as they were with 
metaphysical notions of the Deity (which Dr Genesius terms 
puriores) have constantly had recourse to this interpretation, 
whenever the appearance of God was mentioned in the Scrip- 
tures." Again, in several parts of the Bible, the Divine pre- 
sence is associated with that of Angelic presence : — Compare, 
for example, Exod. iii. 2 with Exod. iii. 4, 6, 7, 11, 13, and, 
particularly, 14, and with Acts vii. 30, 31, 32, 33, and 35 ; 
and, again, Acts vii. 38 with Exod. xix. 3. Further, as is 
maintained by the Eev. J. G. Wright, it might be shewn, 
from a consideration of the context and the general scope of 
the argument, that St Paul's meaning, in his reference to the 
eighth Psalm in Heb. il. 7, although he uses the word Angels 
(herein following the Septuagint version, as our translators 
have done), is intelligible only when the word angels is used 
in its highest sense, e. the primary and proper sense of 
Elohim, The Apostle's object is to shew the superiority of our 
Lord Jesus Christ, in his hi; man nature, over the nature of 
Angels, and this he does by shewing the superiority of mans 
nature. 



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